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 local cert_verify_identity = require "util.x509".verify_identity;
  31
  32 local fire_event = prosody.events.fire_event;
  33 local uuid_gen = require "util.uuid".generate;
  34
  35 local logger_init = require "util.logger".init;
  36
  37 local log = logger_init("s2smanager");
  38
  39 local sha256_hash = require "util.hashes".sha256;
  40
  41 local adns, dns = require "net.adns", require "net.dns";
  42 local config = require "core.configmanager";
  43 local connect_timeout = config.get("*", "core", "s2s_timeout") or 60;
  44 local dns_timeout = config.get("*", "core", "dns_timeout") or 15;
  45 local max_dns_depth = config.get("*", "core", "dns_max_depth") or 3;
  46
  47 dns.settimeout(dns_timeout);
  48
  49 local prosody = _G.prosody;
  50 incoming_s2s = {};
  51 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                         if reply and not(reply.attr.xmlns) and bouncy_stanzas[reply.name] then
  75                                 reply.attr.type = "error";
  76                                 reply:tag("error", {type = "cancel"})
  77                                         :tag("remote-server-not-found", {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"}):up();
  78                                 if reason then
  79                                         reply:tag("text", {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"}):text("Connection failed: "..reason):up();
  80                                 end
  81                                 core_process_stanza(dummy, reply);
  82                         end
  83                         sendq[i] = nil;
  84                 end
  85                 session.sendq = nil;
  86         end
  87 end
  88
  89 function send_to_host(from_host, to_host, data)
  90         if not hosts[from_host] then
  91                 log("warn", "Attempt to send stanza from %s - a host we don't serve", from_host);
  92                 return false;
  93         end
  94         local host = hosts[from_host].s2sout[to_host];
  95         if host then
  96                 -- We have a connection to this host already
  97                 if host.type == "s2sout_unauthed" and (data.name ~= "db:verify" or not host.dialback_key) then
  98                         (host.log or log)("debug", "trying to send over unauthed s2sout to "..to_host);
  99
 100                         -- Queue stanza until we are able to send it
 101                         if host.sendq then t_insert(host.sendq, {tostring(data), data.attr.type ~= "error" and data.attr.type ~= "result" and st.reply(data)});
 102                         else host.sendq = { {tostring(data), data.attr.type ~= "error" and data.attr.type ~= "result" and st.reply(data)} }; end
 103                         host.log("debug", "stanza [%s] queued ", data.name);
 104                 elseif host.type == "local" or host.type == "component" then
 105                         log("error", "Trying to send a stanza to ourselves??")
 106                         log("error", "Traceback: %s", get_traceback());
 107                         log("error", "Stanza: %s", tostring(data));
 108                         return false;
 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), data.attr.type ~= "error" and data.attr.type ~= "result" and 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                         if not destroy_session(host_session, "Connection failed") then
 129                                 -- Already destroyed, we need to bounce our stanza
 130                                 bounce_sendq(host_session, host_session.destruction_reason);
 131                         end
 132                         return false;
 133                 end
 134         end
 135         return true;
 136 end
 137
 138 local open_sessions = 0;
 139
 140 function new_incoming(conn)
 141         local session = { conn = conn, type = "s2sin_unauthed", direction = "incoming", hosts = {} };
 142         if true then
 143                 session.trace = newproxy(true);
 144                 getmetatable(session.trace).__gc = function () open_sessions = open_sessions - 1; end;
 145         end
 146         open_sessions = open_sessions + 1;
 147         local w, log = conn.write, logger_init("s2sin"..tostring(conn):match("[a-f0-9]+$"));
 148         session.log = log;
 149         local filter = initialize_filters(session);
 150         session.sends2s = function (t)
 151                 log("debug", "sending: %s", t.top_tag and t:top_tag() or t:match("^([^>]*>?)"));
 152                 if t.name then
 153                         t = filter("stanzas/out", t);
 154                 end
 155                 if t then
 156                         t = filter("bytes/out", tostring(t));
 157                         if t then
 158                                 return w(conn, t);
 159                         end
 160                 end
 161         end
 162         incoming_s2s[session] = true;
 163         add_task(connect_timeout, function ()
 164                 if session.conn ~= conn or
 165                    session.type == "s2sin" then
 166                         return; -- Ok, we're connect[ed|ing]
 167                 end
 168                 -- Not connected, need to close session and clean up
 169                 (session.log or log)("warn", "Destroying incomplete session %s->%s due to inactivity",
 170                     session.from_host or "(unknown)", session.to_host or "(unknown)");
 171                 session:close("connection-timeout");
 172         end);
 173         return session;
 174 end
 175
 176 function new_outgoing(from_host, to_host, connect)
 177                 local host_session = { to_host = to_host, from_host = from_host, host = from_host,
 178                                        notopen = true, type = "s2sout_unauthed", direction = "outgoing",
 179                                        open_stream = session_open_stream };
 180
 181                 hosts[from_host].s2sout[to_host] = host_session;
 182
 183                 host_session.close = destroy_session; -- This gets replaced by xmppserver_listener later
 184
 185                 local log;
 186                 do
 187                         local conn_name = "s2sout"..tostring(host_session):match("[a-f0-9]*$");
 188                         log = logger_init(conn_name);
 189                         host_session.log = log;
 190                 end
 191
 192                 initialize_filters(host_session);
 193
 194                 if connect ~= false then
 195                         -- Kick the connection attempting machine into life
 196                         if not attempt_connection(host_session) then
 197                                 -- Intentionally not returning here, the
 198                                 -- session is needed, connected or not
 199                                 destroy_session(host_session);
 200                         end
 201                 end
 202
 203                 if not host_session.sends2s then
 204                         -- A sends2s which buffers data (until the stream is opened)
 205                         -- note that data in this buffer will be sent before the stream is authed
 206                         -- and will not be ack'd in any way, successful or otherwise
 207                         local buffer;
 208                         function host_session.sends2s(data)
 209                                 if not buffer then
 210                                         buffer = {};
 211                                         host_session.send_buffer = buffer;
 212                                 end
 213                                 log("debug", "Buffering data on unconnected s2sout to %s", to_host);
 214                                 buffer[#buffer+1] = data;
 215                                 log("debug", "Buffered item %d: %s", #buffer, tostring(data));
 216                         end
 217                 end
 218
 219                 return host_session;
 220 end
 221
 222
 223 function attempt_connection(host_session, err)
 224         local from_host, to_host = host_session.from_host, host_session.to_host;
 225         local connect_host, connect_port = to_host and idna_to_ascii(to_host), 5269;
 226
 227         if not connect_host then
 228                 return false;
 229         end
 230
 231         if not err then -- This is our first attempt
 232                 log("debug", "First attempt to connect to %s, starting with SRV lookup...", to_host);
 233                 host_session.connecting = true;
 234                 local handle;
 235                 handle = adns.lookup(function (answer)
 236                         handle = nil;
 237                         host_session.connecting = nil;
 238                         if answer then
 239                                 log("debug", to_host.." has SRV records, handling...");
 240                                 local srv_hosts = {};
 241                                 host_session.srv_hosts = srv_hosts;
 242                                 for _, record in ipairs(answer) do
 243                                         t_insert(srv_hosts, record.srv);
 244                                 end
 245                                 t_sort(srv_hosts, compare_srv_priorities);
 246
 247                                 local srv_choice = srv_hosts[1];
 248                                 host_session.srv_choice = 1;
 249                                 if srv_choice then
 250                                         connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
 251                                         log("debug", "Best record found, will connect to %s:%d", connect_host, connect_port);
 252                                 end
 253                         else
 254                                 log("debug", to_host.." has no SRV records, falling back to A");
 255                         end
 256                         -- Try with SRV, or just the plain hostname if no SRV
 257                         local ok, err = try_connect(host_session, connect_host, connect_port);
 258                         if not ok then
 259                                 if not attempt_connection(host_session, err) then
 260                                         -- No more attempts will be made
 261                                         destroy_session(host_session, err);
 262                                 end
 263                         end
 264                 end, "_xmpp-server._tcp."..connect_host..".", "SRV");
 265
 266                 return true; -- Attempt in progress
 267         elseif host_session.srv_hosts and #host_session.srv_hosts > host_session.srv_choice then -- Not our first attempt, and we also have SRV
 268                 host_session.srv_choice = host_session.srv_choice + 1;
 269                 local srv_choice = host_session.srv_hosts[host_session.srv_choice];
 270                 connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
 271                 host_session.log("info", "Connection failed (%s). Attempt #%d: This time to %s:%d", tostring(err), host_session.srv_choice, connect_host, connect_port);
 272         else
 273                 host_session.log("info", "Out of connection options, can't connect to %s", tostring(host_session.to_host));
 274                 -- We're out of options
 275                 return false;
 276         end
 277
 278         if not (connect_host and connect_port) then
 279                 -- Likely we couldn't resolve DNS
 280                 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));
 281                 return false;
 282         end
 283
 284         return try_connect(host_session, connect_host, connect_port);
 285 end
 286
 287 function try_connect(host_session, connect_host, connect_port)
 288         host_session.connecting = true;
 289         local handle;
 290         handle = adns.lookup(function (reply, err)
 291                 handle = nil;
 292                 host_session.connecting = nil;
 293
 294                 -- COMPAT: This is a compromise for all you CNAME-(ab)users :)
 295                 if not (reply and reply[#reply] and reply[#reply].a) then
 296                         local count = max_dns_depth;
 297                         reply = dns.peek(connect_host, "CNAME", "IN");
 298                         while count > 0 and reply and reply[#reply] and not reply[#reply].a and reply[#reply].cname do
 299                                 log("debug", "Looking up %s (DNS depth is %d)", tostring(reply[#reply].cname), count);
 300                                 reply = dns.peek(reply[#reply].cname, "A", "IN") or dns.peek(reply[#reply].cname, "CNAME", "IN");
 301                                 count = count - 1;
 302                         end
 303                 end
 304                 -- end of CNAME resolving
 305
 306                 if reply and reply[#reply] and reply[#reply].a then
 307                         log("debug", "DNS reply for %s gives us %s", connect_host, reply[#reply].a);
 308                         local ok, err = make_connect(host_session, reply[#reply].a, connect_port);
 309                         if not ok then
 310                                 if not attempt_connection(host_session, err or "closed") then
 311                                         err = err and (": "..err) or "";
 312                                         destroy_session(host_session, "Connection failed"..err);
 313                                 end
 314                         end
 315                 else
 316                         log("debug", "DNS lookup failed to get a response for %s", connect_host);
 317                         if not attempt_connection(host_session, "name resolution failed") then -- Retry if we can
 318                                 log("debug", "No other records to try for %s - destroying", host_session.to_host);
 319                                 err = err and (": "..err) or "";
 320                                 destroy_session(host_session, "DNS resolution failed"..err); -- End of the line, we can't
 321                         end
 322                 end
 323         end, connect_host, "A", "IN");
 324
 325         return true;
 326 end
 327
 328 function make_connect(host_session, connect_host, connect_port)
 329         (host_session.log or log)("info", "Beginning new connection attempt to %s (%s:%d)", host_session.to_host, connect_host, connect_port);
 330         -- Ok, we're going to try to connect
 331
 332         local from_host, to_host = host_session.from_host, host_session.to_host;
 333
 334         local conn, handler = socket.tcp();
 335
 336         if not conn then
 337                 log("warn", "Failed to create outgoing connection, system error: %s", handler);
 338                 return false, handler;
 339         end
 340
 341         conn:settimeout(0);
 342         local success, err = conn:connect(connect_host, connect_port);
 343         if not success and err ~= "timeout" then
 344                 log("warn", "s2s connect() to %s (%s:%d) failed: %s", host_session.to_host, connect_host, connect_port, err);
 345                 return false, err;
 346         end
 347
 348         local cl = connlisteners_get("xmppserver");
 349         conn = wrapclient(conn, connect_host, connect_port, cl, cl.default_mode or 1 );
 350         host_session.conn = conn;
 351
 352         local filter = initialize_filters(host_session);
 353         local w, log = conn.write, host_session.log;
 354         host_session.sends2s = function (t)
 355                 log("debug", "sending: %s", (t.top_tag and t:top_tag()) or t:match("^[^>]*>?"));
 356                 if t.name then
 357                         t = filter("stanzas/out", t);
 358                 end
 359                 if t then
 360                         t = filter("bytes/out", tostring(t));
 361                         if t then
 362                                 return w(conn, tostring(t));
 363                         end
 364                 end
 365         end
 366
 367         -- Register this outgoing connection so that xmppserver_listener knows about it
 368         -- otherwise it will assume it is a new incoming connection
 369         cl.register_outgoing(conn, host_session);
 370
 371         host_session:open_stream(from_host, to_host);
 372
 373         log("debug", "Connection attempt in progress...");
 374         add_task(connect_timeout, function ()
 375                 if host_session.conn ~= conn or
 376                    host_session.type == "s2sout" or
 377                    host_session.connecting then
 378                         return; -- Ok, we're connect[ed|ing]
 379                 end
 380                 -- Not connected, need to close session and clean up
 381                 (host_session.log or log)("warn", "Destroying incomplete session %s->%s due to inactivity",
 382                     host_session.from_host or "(unknown)", host_session.to_host or "(unknown)");
 383                 host_session:close("connection-timeout");
 384         end);
 385         return true;
 386 end
 387
 388 function session_open_stream(session, from, to)
 389         session.sends2s(st.stanza("stream:stream", {
 390                 xmlns='jabber:server', ["xmlns:db"]='jabber:server:dialback',
 391                 ["xmlns:stream"]='http://etherx.jabber.org/streams',
 392                 from=from, to=to, version='1.0', ["xml:lang"]='en'}):top_tag());
 393 end
 394
 395 local function check_cert_status(session)
 396         local conn = session.conn:socket()
 397         local cert
 398         if conn.getpeercertificate then
 399                 cert = conn:getpeercertificate()
 400         end
 401
 402         if cert then
 403                 local chain_valid, err = conn:getpeerchainvalid()
 404                 if not chain_valid then
 405                         session.cert_chain_status = "invalid";
 406                         (session.log or log)("debug", "certificate chain validation result: %s", err);
 407                 else
 408                         session.cert_chain_status = "valid";
 409
 410                         local host = session.direction == "incoming" and session.from_host or session.to_host
 411
 412                         -- We'll go ahead and verify the asserted identity if the
 413                         -- connecting server specified one.
 414                         if host then
 415                                 if cert_verify_identity(host, "xmpp-server", cert) then
 416                                         session.cert_identity_status = "valid"
 417                                 else
 418                                         session.cert_identity_status = "invalid"
 419                                 end
 420                         end
 421                 end
 422         end
 423 end
 424
 425 function streamopened(session, attr)
 426         local send = session.sends2s;
 427
 428         -- TODO: #29: SASL/TLS on s2s streams
 429         session.version = tonumber(attr.version) or 0;
 430
 431         -- TODO: Rename session.secure to session.encrypted
 432         if session.secure == false then
 433                 session.secure = true;
 434         end
 435
 436         if session.direction == "incoming" then
 437                 -- Send a reply stream header
 438                 session.to_host = attr.to and nameprep(attr.to);
 439                 session.from_host = attr.from and nameprep(attr.from);
 440
 441                 session.streamid = uuid_gen();
 442                 (session.log or log)("debug", "incoming s2s received <stream:stream>");
 443                 if session.to_host then
 444                         if not hosts[session.to_host] then
 445                                 -- Attempting to connect to a host we don't serve
 446                                 session:close({
 447                                         condition = "host-unknown";
 448                                         text = "This host does not serve "..session.to_host
 449                                 });
 450                                 return;
 451                         elseif hosts[session.to_host].disallow_s2s then
 452                                 -- Attempting to connect to a host that disallows s2s
 453                                 session:close({
 454                                         condition = "policy-violation";
 455                                         text = "Server-to-server communication is not allowed to this host";
 456                                 });
 457                                 return;
 458                         end
 459                 end
 460
 461                 if session.secure and not session.cert_chain_status then check_cert_status(session); end
 462
 463                 send("<?xml version='1.0'?>");
 464                 send(stanza("stream:stream", { xmlns='jabber:server', ["xmlns:db"]='jabber:server:dialback',
 465                                 ["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());
 466                 if session.version >= 1.0 then
 467                         local features = st.stanza("stream:features");
 468
 469                         if session.to_host then
 470                                 hosts[session.to_host].events.fire_event("s2s-stream-features", { origin = session, features = features });
 471                         else
 472                                 (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");
 473                         end
 474
 475                         log("debug", "Sending stream features: %s", tostring(features));
 476                         send(features);
 477                 end
 478         elseif session.direction == "outgoing" then
 479                 -- If we are just using the connection for verifying dialback keys, we won't try and auth it
 480                 if not attr.id then error("stream response did not give us a streamid!!!"); end
 481                 session.streamid = attr.id;
 482
 483                 if session.secure and not session.cert_chain_status then check_cert_status(session); end
 484
 485                 -- Send unauthed buffer
 486                 -- (stanzas which are fine to send before dialback)
 487                 -- Note that this is *not* the stanza queue (which
 488                 -- we can only send if auth succeeds) :)
 489                 local send_buffer = session.send_buffer;
 490                 if send_buffer and #send_buffer > 0 then
 491                         log("debug", "Sending s2s send_buffer now...");
 492                         for i, data in ipairs(send_buffer) do
 493                                 session.sends2s(tostring(data));
 494                                 send_buffer[i] = nil;
 495                         end
 496                 end
 497                 session.send_buffer = nil;
 498
 499                 -- If server is pre-1.0, don't wait for features, just do dialback
 500                 if session.version < 1.0 then
 501                         if not session.dialback_verifying then
 502                                 log("debug", "Initiating dialback...");
 503                                 initiate_dialback(session);
 504                         else
 505                                 mark_connected(session);
 506                         end
 507                 end
 508         end
 509         session.notopen = nil;
 510 end
 511
 512 function streamclosed(session)
 513         (session.log or log)("debug", "Received </stream:stream>");
 514         session:close();
 515 end
 516
 517 function initiate_dialback(session)
 518         -- generate dialback key
 519         session.dialback_key = generate_dialback(session.streamid, session.to_host, session.from_host);
 520         session.sends2s(format("<db:result from='%s' to='%s'>%s</db:result>", session.from_host, session.to_host, session.dialback_key));
 521         session.log("info", "sent dialback key on outgoing s2s stream");
 522 end
 523
 524 function generate_dialback(id, to, from)
 525         return sha256_hash(id..to..from..hosts[from].dialback_secret, true);
 526 end
 527
 528 function verify_dialback(id, to, from, key)
 529         return key == generate_dialback(id, to, from);
 530 end
 531
 532 function make_authenticated(session, host)
 533         if not session.secure then
 534                 local local_host = session.direction == "incoming" and session.to_host or session.from_host;
 535                 if config.get(local_host, "core", "s2s_require_encryption") then
 536                         session:close({
 537                                 condition = "policy-violation",
 538                                 text = "Encrypted server-to-server communication is required but was not "
 539                                        ..((session.direction == "outgoing" and "offered") or "used")
 540                         });
 541                 end
 542         end
 543         if session.type == "s2sout_unauthed" then
 544                 session.type = "s2sout";
 545         elseif session.type == "s2sin_unauthed" then
 546                 session.type = "s2sin";
 547                 if host then
 548                         if not session.hosts[host] then session.hosts[host] = {}; end
 549                         session.hosts[host].authed = true;
 550                 end
 551         elseif session.type == "s2sin" and host then
 552                 if not session.hosts[host] then session.hosts[host] = {}; end
 553                 session.hosts[host].authed = true;
 554         else
 555                 return false;
 556         end
 557         session.log("debug", "connection %s->%s is now authenticated", session.from_host or "(unknown)", session.to_host or "(unknown)");
 558
 559         mark_connected(session);
 560
 561         return true;
 562 end
 563
 564 -- Stream is authorised, and ready for normal stanzas
 565 function mark_connected(session)
 566         local sendq, send = session.sendq, session.sends2s;
 567
 568         local from, to = session.from_host, session.to_host;
 569
 570         session.log("info", session.direction.." s2s connection "..from.."->"..to.." complete");
 571
 572         local send_to_host = send_to_host;
 573         function session.send(data) return send_to_host(to, from, data); end
 574
 575         local event_data = { session = session };
 576         if session.type == "s2sout" then
 577                 prosody.events.fire_event("s2sout-established", event_data);
 578                 hosts[session.from_host].events.fire_event("s2sout-established", event_data);
 579         else
 580                 prosody.events.fire_event("s2sin-established", event_data);
 581                 hosts[session.to_host].events.fire_event("s2sin-established", event_data);
 582         end
 583
 584         if session.direction == "outgoing" then
 585                 if sendq then
 586                         session.log("debug", "sending "..#sendq.." queued stanzas across new outgoing connection to "..session.to_host);
 587                         for i, data in ipairs(sendq) do
 588                                 send(data[1]);
 589                                 sendq[i] = nil;
 590                         end
 591                         session.sendq = nil;
 592                 end
 593
 594                 session.srv_hosts = nil;
 595         end
 596 end
 597
 598 local resting_session = { -- Resting, not dead
 599                 destroyed = true;
 600                 type = "s2s_destroyed";
 601                 open_stream = function (session)
 602                         session.log("debug", "Attempt to open stream on resting session");
 603                 end;
 604                 close = function (session)
 605                         session.log("debug", "Attempt to close already-closed session");
 606                 end;
 607                 filter = function (type, data) return data; end;
 608         }; resting_session.__index = resting_session;
 609
 610 function retire_session(session, reason)
 611         local log = session.log or log;
 612         for k in pairs(session) do
 613                 if k ~= "trace" and k ~= "log" and k ~= "id" then
 614                         session[k] = nil;
 615                 end
 616         end
 617
 618         session.destruction_reason = reason;
 619
 620         function session.send(data) log("debug", "Discarding data sent to resting session: %s", tostring(data)); end
 621         function session.data(data) log("debug", "Discarding data received from resting session: %s", tostring(data)); end
 622         return setmetatable(session, resting_session);
 623 end
 624
 625 function destroy_session(session, reason)
 626         if session.destroyed then return; end
 627         (session.log or log)("info", "Destroying "..tostring(session.direction).." session "..tostring(session.from_host).."->"..tostring(session.to_host));
 628
 629         if session.direction == "outgoing" then
 630                 hosts[session.from_host].s2sout[session.to_host] = nil;
 631                 bounce_sendq(session, reason);
 632         elseif session.direction == "incoming" then
 633                 incoming_s2s[session] = nil;
 634         end
 635
 636         local event_data = { session = session, reason = reason };
 637         if session.type == "s2sout" then
 638                 prosody.events.fire_event("s2sout-destroyed", event_data);
 639                 if hosts[session.from_host] then
 640                         hosts[session.from_host].events.fire_event("s2sout-destroyed", event_data);
 641                 end
 642         elseif session.type == "s2sin" then
 643                 prosody.events.fire_event("s2sin-destroyed", event_data);
 644                 if hosts[session.to_host] then
 645                         hosts[session.to_host].events.fire_event("s2sin-destroyed", event_data);
 646                 end
 647         end
 648
 649         retire_session(session, reason); -- Clean session until it is GC'd
 650         return true;
 651 end
 652
 653 return _M;