aboutsummaryrefslogtreecommitdiffstats
path: root/plugins/mod_s2s/mod_s2s.lua
blob: c288d85849b53b127bbe0ebf15c25964268042a3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
-- Prosody IM
-- Copyright (C) 2008-2010 Matthew Wild
-- Copyright (C) 2008-2010 Waqas Hussain
-- 
-- This project is MIT/X11 licensed. Please see the
-- COPYING file in the source package for more information.
--

module:set_global();

local prosody = prosody;
local hosts = prosody.hosts;
local core_process_stanza = prosody.core_process_stanza;

local tostring, type = tostring, type;
local t_insert = table.insert;
local xpcall, traceback = xpcall, debug.traceback;
local NULL = {};

local add_task = require "util.timer".add_task;
local st = require "util.stanza";
local initialize_filters = require "util.filters".initialize;
local nameprep = require "util.encodings".stringprep.nameprep;
local new_xmpp_stream = require "util.xmppstream".new;
local s2s_new_incoming = require "core.s2smanager".new_incoming;
local s2s_new_outgoing = require "core.s2smanager".new_outgoing;
local s2s_destroy_session = require "core.s2smanager".destroy_session;
local uuid_gen = require "util.uuid".generate;
local cert_verify_identity = require "util.x509".verify_identity;
local fire_global_event = prosody.events.fire_event;

local s2sout = module:require("s2sout");

local connect_timeout = module:get_option_number("s2s_timeout", 90);
local stream_close_timeout = module:get_option_number("s2s_close_timeout", 5);
local opt_keepalives = module:get_option_boolean("s2s_tcp_keepalives", module:get_option_boolean("tcp_keepalives", true));
local secure_auth = module:get_option_boolean("s2s_secure_auth", false); -- One day...
local secure_domains, insecure_domains =
	module:get_option_set("s2s_secure_domains", {})._items, module:get_option_set("s2s_insecure_domains", {})._items;
local require_encryption = module:get_option_boolean("s2s_require_encryption", false);

local sessions = module:shared("sessions");

local log = module._log;

--- Handle stanzas to remote domains

local bouncy_stanzas = { message = true, presence = true, iq = true };
local function bounce_sendq(session, reason)
	local sendq = session.sendq;
	if not sendq then return; end
	session.log("info", "sending error replies for "..#sendq.." queued stanzas because of failed outgoing connection to "..tostring(session.to_host));
	local dummy = {
		type = "s2sin";
		send = function(s)
			(session.log or log)("error", "Replying to to an s2s error reply, please report this! Traceback: %s", traceback());
		end;
		dummy = true;
	};
	for i, data in ipairs(sendq) do
		local reply = data[2];
		if reply and not(reply.attr.xmlns) and bouncy_stanzas[reply.name] then
			reply.attr.type = "error";
			reply:tag("error", {type = "cancel"})
				:tag("remote-server-not-found", {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"}):up();
			if reason then
				reply:tag("text", {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"})
					:text("Server-to-server connection failed: "..reason):up();
			end
			core_process_stanza(dummy, reply);
		end
		sendq[i] = nil;
	end
	session.sendq = nil;
end

-- Handles stanzas to existing s2s sessions
function route_to_existing_session(event)
	local from_host, to_host, stanza = event.from_host, event.to_host, event.stanza;
	if not hosts[from_host] then
		log("warn", "Attempt to send stanza from %s - a host we don't serve", from_host);
		return false;
	end
	if hosts[to_host] then
		log("warn", "Attempt to route stanza to a remote %s - a host we do serve?!", from_host);
		return false;
	end
	local host = hosts[from_host].s2sout[to_host];
	if host then
		-- We have a connection to this host already
		if host.type == "s2sout_unauthed" and (stanza.name ~= "db:verify" or not host.dialback_key) then
			(host.log or log)("debug", "trying to send over unauthed s2sout to "..to_host);

			-- Queue stanza until we are able to send it
			if host.sendq then t_insert(host.sendq, {tostring(stanza), stanza.attr.type ~= "error" and stanza.attr.type ~= "result" and st.reply(stanza)});
			else host.sendq = { {tostring(stanza), stanza.attr.type ~= "error" and stanza.attr.type ~= "result" and st.reply(stanza)} }; end
			host.log("debug", "stanza [%s] queued ", stanza.name);
			return true;
		elseif host.type == "local" or host.type == "component" then
			log("error", "Trying to send a stanza to ourselves??")
			log("error", "Traceback: %s", traceback());
			log("error", "Stanza: %s", tostring(stanza));
			return false;
		else
			(host.log or log)("debug", "going to send stanza to "..to_host.." from "..from_host);
			-- FIXME
			if host.from_host ~= from_host then
				log("error", "WARNING! This might, possibly, be a bug, but it might not...");
				log("error", "We are going to send from %s instead of %s", tostring(host.from_host), tostring(from_host));
			end
			if host.sends2s(stanza) then
				host.log("debug", "stanza sent over %s", host.type);
				return true;
			end
		end
	end
end

-- Create a new outgoing session for a stanza
function route_to_new_session(event)
	local from_host, to_host, stanza = event.from_host, event.to_host, event.stanza;
	log("debug", "opening a new outgoing connection for this stanza");
	local host_session = s2s_new_outgoing(from_host, to_host);

	-- Store in buffer
	host_session.bounce_sendq = bounce_sendq;
	host_session.sendq = { {tostring(stanza), stanza.attr.type ~= "error" and stanza.attr.type ~= "result" and st.reply(stanza)} };
	log("debug", "stanza [%s] queued until connection complete", tostring(stanza.name));
	s2sout.initiate_connection(host_session);
	if (not host_session.connecting) and (not host_session.conn) then
		log("warn", "Connection to %s failed already, destroying session...", to_host);
		s2s_destroy_session(host_session, "Connection failed");
		return false;
	end
	return true;
end

function module.add_host(module)
	if module:get_option_boolean("disallow_s2s", false) then
		module:log("warn", "The 'disallow_s2s' config option is deprecated, please see http://prosody.im/doc/s2s#disabling");
		return nil, "This host has disallow_s2s set";
	end
	module:hook("route/remote", route_to_existing_session, -1);
	module:hook("route/remote", route_to_new_session, -10);
	module:hook("s2s-authenticated", make_authenticated, -1);
end

-- Stream is authorised, and ready for normal stanzas
function mark_connected(session)
	local sendq, send = session.sendq, session.sends2s;
	
	local from, to = session.from_host, session.to_host;
	
	session.log("info", "%s s2s connection %s->%s complete", session.direction, from, to);

	local event_data = { session = session };
	if session.type == "s2sout" then
		fire_global_event("s2sout-established", event_data);
		hosts[from].events.fire_event("s2sout-established", event_data);
	else
		local host_session = hosts[to];
		session.send = function(stanza)
			return host_session.events.fire_event("route/remote", { from_host = to, to_host = from, stanza = stanza });
		end;

		fire_global_event("s2sin-established", event_data);
		hosts[to].events.fire_event("s2sin-established", event_data);
	end
	
	if session.direction == "outgoing" then
		if sendq then
			session.log("debug", "sending %d queued stanzas across new outgoing connection to %s", #sendq, session.to_host);
			for i, data in ipairs(sendq) do
				send(data[1]);
				sendq[i] = nil;
			end
			session.sendq = nil;
		end
		
		session.ip_hosts = nil;
		session.srv_hosts = nil;
	end
end

function make_authenticated(event)
	local session, host = event.session, event.host;
	if not session.secure then
		if require_encryption or (secure_auth and not(insecure_domains[host])) or secure_domains[host] then
			session:close({
				condition = "policy-violation",
				text = "Encrypted server-to-server communication is required but was not "
				       ..((session.direction == "outgoing" and "offered") or "used")
			});
		end
	end
	if hosts[host] then
		session:close({ condition = "undefined-condition", text = "Attempt to authenticate as a host we serve" });
	end
	if session.type == "s2sout_unauthed" then
		session.type = "s2sout";
	elseif session.type == "s2sin_unauthed" then
		session.type = "s2sin";
		if host then
			if not session.hosts[host] then session.hosts[host] = {}; end
			session.hosts[host].authed = true;
		end
	elseif session.type == "s2sin" and host then
		if not session.hosts[host] then session.hosts[host] = {}; end
		session.hosts[host].authed = true;
	else
		return false;
	end
	session.log("debug", "connection %s->%s is now authenticated for %s", session.from_host, session.to_host, host);
	
	mark_connected(session);
	
	return true;
end

--- Helper to check that a session peer's certificate is valid
local function check_cert_status(session)
	local host = session.direction == "outgoing" and session.to_host or session.from_host
	local conn = session.conn:socket()
	local cert
	if conn.getpeercertificate then
		cert = conn:getpeercertificate()
	end

	if cert then
		local chain_valid, errors;
		if conn.getpeerverification then
			chain_valid, errors = conn:getpeerverification();
		elseif conn.getpeerchainvalid then -- COMPAT mw/luasec-hg
			chain_valid, errors = conn:getpeerchainvalid();
			errors = (not chain_valid) and { { errors } } or nil;
		else
			chain_valid, errors = false, { { "Chain verification not supported by this version of LuaSec" } };
		end
		-- Is there any interest in printing out all/the number of errors here?
		if not chain_valid then
			(session.log or log)("debug", "certificate chain validation result: invalid");
			for depth, t in pairs(errors or NULL) do
				(session.log or log)("debug", "certificate error(s) at depth %d: %s", depth-1, table.concat(t, ", "))
			end
			session.cert_chain_status = "invalid";
		else
			(session.log or log)("debug", "certificate chain validation result: valid");
			session.cert_chain_status = "valid";

			-- We'll go ahead and verify the asserted identity if the
			-- connecting server specified one.
			if host then
				if cert_verify_identity(host, "xmpp-server", cert) then
					session.cert_identity_status = "valid"
				else
					session.cert_identity_status = "invalid"
				end
				(session.log or log)("debug", "certificate identity validation result: %s", session.cert_identity_status);
			end
		end
	end
	return module:fire_event("s2s-check-certificate", { host = host, session = session, cert = cert });
end

--- XMPP stream event handlers

local stream_callbacks = { default_ns = "jabber:server", handlestanza =  core_process_stanza };

local xmlns_xmpp_streams = "urn:ietf:params:xml:ns:xmpp-streams";

function stream_callbacks.streamopened(session, attr)
	local send = session.sends2s;
	
	session.version = tonumber(attr.version) or 0;
	
	-- TODO: Rename session.secure to session.encrypted
	if session.secure == false then
		session.secure = true;

		-- Check if TLS compression is used
		local sock = session.conn:socket();
		if sock.info then
			session.compressed = sock:info"compression";
		elseif sock.compression then
			session.compressed = sock:compression(); --COMPAT mw/luasec-hg
		end
	end

	if session.direction == "incoming" then
		-- Send a reply stream header
		
		-- Validate to/from
		local to, from = nameprep(attr.to), nameprep(attr.from);
		if not to and attr.to then -- COMPAT: Some servers do not reliably set 'to' (especially on stream restarts)
			session:close({ condition = "improper-addressing", text = "Invalid 'to' address" });
			return;
		end
		if not from and attr.from then -- COMPAT: Some servers do not reliably set 'from' (especially on stream restarts)
			session:close({ condition = "improper-addressing", text = "Invalid 'from' address" });
			return;
		end
		
		-- Set session.[from/to]_host if they have not been set already and if
		-- this session isn't already authenticated
		if session.type == "s2sin_unauthed" and from and not session.from_host then
			session.from_host = from;
		elseif from ~= session.from_host then
			session:close({ condition = "improper-addressing", text = "New stream 'from' attribute does not match original" });
			return;
		end
		if session.type == "s2sin_unauthed" and to and not session.to_host then
			session.to_host = to;
		elseif to ~= session.to_host then
			session:close({ condition = "improper-addressing", text = "New stream 'to' attribute does not match original" });
			return;
		end
		
		-- For convenience we'll put the sanitised values into these variables
		to, from = session.to_host, session.from_host;
		
		session.streamid = uuid_gen();
		(session.log or log)("debug", "Incoming s2s received %s", st.stanza("stream:stream", attr):top_tag());
		if to then
			if not hosts[to] then
				-- Attempting to connect to a host we don't serve
				session:close({
					condition = "host-unknown";
					text = "This host does not serve "..to
				});
				return;
			elseif not hosts[to].modules.s2s then
				-- Attempting to connect to a host that disallows s2s
				session:close({
					condition = "policy-violation";
					text = "Server-to-server communication is disabled for this host";
				});
				return;
			end
		end

		if hosts[from] then
			session:close({ condition = "undefined-condition", text = "Attempt to connect from a host we serve" });
			return;
		end

		if session.secure and not session.cert_chain_status then
			if check_cert_status(session) == false then
				return;
			end
		end

		session:open_stream(session.to_host, session.from_host)
		if session.version >= 1.0 then
			local features = st.stanza("stream:features");
			
			if to then
				hosts[to].events.fire_event("s2s-stream-features", { origin = session, features = features });
			else
				(session.log or log)("warn", "No 'to' on stream header from %s means we can't offer any features", from or session.ip or "unknown host");
			end
			
			log("debug", "Sending stream features: %s", tostring(features));
			send(features);
		end
		session.notopen = nil;
	elseif session.direction == "outgoing" then
		session.notopen = nil;
		-- If we are just using the connection for verifying dialback keys, we won't try and auth it
		if not attr.id then error("stream response did not give us a streamid!!!"); end
		session.streamid = attr.id;

		if session.secure and not session.cert_chain_status then
			if check_cert_status(session) == false then
				return;
			end
		end

		-- Send unauthed buffer
		-- (stanzas which are fine to send before dialback)
		-- Note that this is *not* the stanza queue (which
		-- we can only send if auth succeeds) :)
		local send_buffer = session.send_buffer;
		if send_buffer and #send_buffer > 0 then
			log("debug", "Sending s2s send_buffer now...");
			for i, data in ipairs(send_buffer) do
				session.sends2s(tostring(data));
				send_buffer[i] = nil;
			end
		end
		session.send_buffer = nil;
	
		-- If server is pre-1.0, don't wait for features, just do dialback
		if session.version < 1.0 then
			if not session.dialback_verifying then
				hosts[session.from_host].events.fire_event("s2sout-authenticate-legacy", { origin = session });
			else
				mark_connected(session);
			end
		end
	end
end

function stream_callbacks.streamclosed(session)
	(session.log or log)("debug", "Received </stream:stream>");
	session:close(false);
end

function stream_callbacks.error(session, error, data)
	if error == "no-stream" then
		session:close("invalid-namespace");
	elseif error == "parse-error" then
		session.log("debug", "Server-to-server XML parse error: %s", tostring(error));
		session:close("not-well-formed");
	elseif error == "stream-error" then
		local condition, text = "undefined-condition";
		for child in data:children() do
			if child.attr.xmlns == xmlns_xmpp_streams then
				if child.name ~= "text" then
					condition = child.name;
				else
					text = child:get_text();
				end
				if condition ~= "undefined-condition" and text then
					break;
				end
			end
		end
		text = condition .. (text and (" ("..text..")") or "");
		session.log("info", "Session closed by remote with error: %s", text);
		session:close(nil, text);
	end
end

local function handleerr(err) log("error", "Traceback[s2s]: %s", traceback(tostring(err), 2)); end
function stream_callbacks.handlestanza(session, stanza)
	if stanza.attr.xmlns == "jabber:client" then --COMPAT: Prosody pre-0.6.2 may send jabber:client
		stanza.attr.xmlns = nil;
	end
	stanza = session.filter("stanzas/in", stanza);
	if stanza then
		return xpcall(function () return core_process_stanza(session, stanza) end, handleerr);
	end
end

local listener = {};

--- Session methods
local stream_xmlns_attr = {xmlns='urn:ietf:params:xml:ns:xmpp-streams'};
local function session_close(session, reason, remote_reason)
	local log = session.log or log;
	if session.conn then
		if session.notopen then
			if session.direction == "incoming" then
				session:open_stream(session.to_host, session.from_host);
			else
				session:open_stream(session.from_host, session.to_host);
			end
		end
		if reason then -- nil == no err, initiated by us, false == initiated by remote
			if type(reason) == "string" then -- assume stream error
				log("debug", "Disconnecting %s[%s], <stream:error> is: %s", session.host or session.ip or "(unknown host)", session.type, reason);
				session.sends2s(st.stanza("stream:error"):tag(reason, {xmlns = 'urn:ietf:params:xml:ns:xmpp-streams' }));
			elseif type(reason) == "table" then
				if reason.condition then
					local stanza = st.stanza("stream:error"):tag(reason.condition, stream_xmlns_attr):up();
					if reason.text then
						stanza:tag("text", stream_xmlns_attr):text(reason.text):up();
					end
					if reason.extra then
						stanza:add_child(reason.extra);
					end
					log("debug", "Disconnecting %s[%s], <stream:error> is: %s", session.host or session.ip or "(unknown host)", session.type, tostring(stanza));
					session.sends2s(stanza);
				elseif reason.name then -- a stanza
					log("debug", "Disconnecting %s->%s[%s], <stream:error> is: %s", session.from_host or "(unknown host)", session.to_host or "(unknown host)", session.type, tostring(reason));
					session.sends2s(reason);
				end
			end
		end

		session.sends2s("</stream:stream>");
		function session.sends2s() return false; end
		
		local reason = remote_reason or (reason and (reason.text or reason.condition)) or reason;
		session.log("info", "%s s2s stream %s->%s closed: %s", session.direction, session.from_host or "(unknown host)", session.to_host or "(unknown host)", reason or "stream closed");
		
		-- Authenticated incoming stream may still be sending us stanzas, so wait for </stream:stream> from remote
		local conn = session.conn;
		if reason == nil and not session.notopen and session.type == "s2sin" then
			add_task(stream_close_timeout, function ()
				if not session.destroyed then
					session.log("warn", "Failed to receive a stream close response, closing connection anyway...");
					s2s_destroy_session(session, reason);
					conn:close();
				end
			end);
		else
			s2s_destroy_session(session, reason);
			conn:close(); -- Close immediately, as this is an outgoing connection or is not authed
		end
	end
end

function session_open_stream(session, from, to)
	local attr = {
		["xmlns:stream"] = 'http://etherx.jabber.org/streams',
		xmlns = 'jabber:server',
		version = session.version and (session.version > 0 and "1.0" or nil),
		["xml:lang"] = 'en',
		id = session.streamid,
		from = from, to = to,
	}
	if not from or (hosts[from] and hosts[from].modules.dialback) then
		attr["xmlns:db"] = 'jabber:server:dialback';
	end

	session.sends2s("<?xml version='1.0'?>");
	session.sends2s(st.stanza("stream:stream", attr):top_tag());
	return true;
end

-- Session initialization logic shared by incoming and outgoing
local function initialize_session(session)
	local stream = new_xmpp_stream(session, stream_callbacks);
	session.stream = stream;
	
	session.notopen = true;
		
	function session.reset_stream()
		session.notopen = true;
		session.streamid = nil;
		session.stream:reset();
	end

	session.open_stream = session_open_stream;
	
	local filter = session.filter;
	function session.data(data)
		data = filter("bytes/in", data);
		if data then
			local ok, err = stream:feed(data);
			if ok then return; end
			(session.log or log)("warn", "Received invalid XML: %s", data);
			(session.log or log)("warn", "Problem was: %s", err);
			session:close("not-well-formed");
		end
	end

	session.close = session_close;

	local handlestanza = stream_callbacks.handlestanza;
	function session.dispatch_stanza(session, stanza)
		return handlestanza(session, stanza);
	end

	add_task(connect_timeout, function ()
		if session.type == "s2sin" or session.type == "s2sout" then
			return; -- Ok, we're connected
		elseif session.type == "s2s_destroyed" then
			return; -- Session already destroyed
		end
		-- Not connected, need to close session and clean up
		(session.log or log)("debug", "Destroying incomplete session %s->%s due to inactivity",
		session.from_host or "(unknown)", session.to_host or "(unknown)");
		session:close("connection-timeout");
	end);
end

function listener.onconnect(conn)
	conn:setoption("keepalive", opt_keepalives);
	local session = sessions[conn];
	if not session then -- New incoming connection
		session = s2s_new_incoming(conn);
		sessions[conn] = session;
		session.log("debug", "Incoming s2s connection");

		local filter = initialize_filters(session);
		local w = conn.write;
		session.sends2s = function (t)
			log("debug", "sending: %s", t.top_tag and t:top_tag() or t:match("^([^>]*>?)"));
			if t.name then
				t = filter("stanzas/out", t);
			end
			if t then
				t = filter("bytes/out", tostring(t));
				if t then
					return w(conn, t);
				end
			end
		end
	
		initialize_session(session);
	else -- Outgoing session connected
		session:open_stream(session.from_host, session.to_host);
	end
end

function listener.onincoming(conn, data)
	local session = sessions[conn];
	if session then
		session.data(data);
	end
end
	
function listener.onstatus(conn, status)
	if status == "ssl-handshake-complete" then
		local session = sessions[conn];
		if session and session.direction == "outgoing" then
			session.log("debug", "Sending stream header...");
			session:open_stream(session.from_host, session.to_host);
		end
	end
end

function listener.ondisconnect(conn, err)
	local session = sessions[conn];
	if session then
		sessions[conn] = nil;
		if err and session.direction == "outgoing" and session.notopen then
			(session.log or log)("debug", "s2s connection attempt failed: %s", err);
			if s2sout.attempt_connection(session, err) then
				(session.log or log)("debug", "...so we're going to try another target");
				return; -- Session lives for now
			end
		end
		(session.log or log)("debug", "s2s disconnected: %s->%s (%s)", tostring(session.from_host), tostring(session.to_host), tostring(err or "connection closed"));
		s2s_destroy_session(session, err);
	end
end

function listener.register_outgoing(conn, session)
	session.direction = "outgoing";
	sessions[conn] = session;
	initialize_session(session);
end

function check_auth_policy(event)
	local host, session = event.host, event.session;
	local must_secure = secure_auth;

	if not must_secure and secure_domains[host] then
		must_secure = true;
	elseif must_secure and insecure_domains[host] then
		must_secure = false;
	end
	
	if must_secure and (session.cert_chain_status ~= "valid" or session.cert_identity_status ~= "valid") then
		module:log("warn", "Forbidding insecure connection to/from %s", host or session.ip or "(unknown host)");
		if session.direction == "incoming" then
			session:close({ condition = "not-authorized", text = "Your server's certificate is invalid, expired, or not trusted by "..session.to_host });
		else -- Close outgoing connections without warning
			session:close(false);
		end
		return false;
	end
end

module:hook("s2s-check-certificate", check_auth_policy, -1);

s2sout.set_listener(listener);

module:hook("server-stopping", function(event)
	local reason = event.reason;
	for _, session in pairs(sessions) do
		session:close{ condition = "system-shutdown", text = reason };
	end
end,500);



module:provides("net", {
	name = "s2s";
	listener = listener;
	default_port = 5269;
	encryption = "starttls";
	multiplex = {
		pattern = "^<.*:stream.*%sxmlns%s*=%s*(['\"])jabber:server%1.*>";
	};
});