aboutsummaryrefslogtreecommitdiffstats
path: root/plugins/mod_s2s/mod_s2s.lua
blob: 7cd90a8434d5879992cd39d845831f7ea40dfc6f (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
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
-- 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 traceback = debug.traceback;

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 fire_global_event = prosody.events.fire_event;
local runner = require "util.async".runner;
local connect = require "net.connect".connect;
local service = require "net.resolvers.service";
local errors = require "util.error";
local set = require "util.set";

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 measure_connections = module:measure("connections", "amount");
local measure_ipv6 = module:measure("ipv6", "amount");

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

local runner_callbacks = {};

local listener = {};

local log = module._log;

module:hook("stats-update", function ()
	local count = 0;
	local ipv6 = 0;
	for _, session in pairs(sessions) do
		count = count + 1;
		if session.ip and session.ip:match(":") then
			ipv6 = ipv6 + 1;
		end
	end
	measure_connections(count);
	measure_ipv6(ipv6);
end);

--- 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 %d queued stanzas because of failed outgoing connection to %s", #sendq, session.to_host);
	local dummy = {
		type = "s2sin";
		send = function ()
			(session.log or log)("error", "Replying to to an s2s error reply, please report this! Traceback: %s", traceback());
		end;
		dummy = true;
		close = function ()
			(session.log or log)("error", "Attempting to close the dummy origin of s2s error replies, please report this! Traceback: %s", traceback());
		end;
	};
	-- FIXME Allow for more specific error conditions
	-- TODO use util.error ?
	local error_type = "cancel";
	local condition = "remote-server-not-found";
	local reason_text;
	if session.had_stream then -- set when a stream is opened by the remote
		error_type, condition = "wait", "remote-server-timeout";
	end
	if errors.is_err(reason) then
		error_type, condition, reason_text = reason.type, reason.condition, reason.text;
	elseif type(reason) == "string" then
		reason_text = reason;
	end
	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 = error_type, by = session.from_host})
				:tag(condition, {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"}):up();
			if reason_text then
				reply:tag("text", {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"})
					:text("Server-to-server connection failed: "..reason_text):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
			local queued_item = {
				tostring(stanza),
				stanza.attr.type ~= "error" and stanza.attr.type ~= "result" and st.reply(stanza);
			};
			if host.sendq then
				t_insert(host.sendq, queued_item);
			else
				-- luacheck: ignore 122
				host.sendq = { queued_item };
			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", stanza);
			return false;
		else
			if host.sends2s(stanza) then
				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);
	host_session.version = 1;

	-- 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", stanza.name);
	connect(service.new(to_host, "xmpp-server", "tcp", { default_port = 5269 }), listener, nil, { session = host_session });
	return true;
end

local function keepalive(event)
	return event.session.sends2s(' ');
end

module:hook("s2s-read-timeout", keepalive, -1);

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 https://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);
	module:hook("s2s-read-timeout", keepalive, -1);
	module:hook_stanza("http://etherx.jabber.org/streams", "features", function (session, stanza) -- luacheck: ignore 212/stanza
		if session.type == "s2sout" then
			-- Stream is authenticated and we are seem to be done with feature negotiation,
			-- so the stream is ready for stanzas.  RFC 6120 Section 4.3
			mark_connected(session);
			return true;
		elseif require_encryption and not session.secure then
			session.log("warn", "Encrypted server-to-server communication is required but was not offered by %s", session.to_host);
			session:close({
					condition = "policy-violation",
					text = "Encrypted server-to-server communication is required but was not offered",
				}, nil, "Could not establish encrypted connection to remote server");
			return true;
		elseif not session.dialback_verifying then
			session.log("warn", "No SASL EXTERNAL offer and Dialback doesn't seem to be enabled, giving up");
			session:close({
					condition = "unsupported-feature",
					text = "No viable authentication method offered",
				}, nil, "No viable authentication method offered by remote server");
			return true;
		end
	end, -1);
end

-- Stream is authorised, and ready for normal stanzas
function mark_connected(session)

	local sendq = session.sendq;

	local from, to = session.from_host, session.to_host;

	session.log("info", "%s s2s connection %s->%s complete", session.direction:gsub("^.", string.upper), 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);

		if session.incoming then
			session.send = function(stanza)
				return hosts[from].events.fire_event("route/remote", { from_host = from, to_host = to, stanza = stanza });
			end;
		end

	else
		if session.outgoing and not hosts[to].s2sout[from] then
			session.log("debug", "Setting up to handle route from %s to %s", to, from);
			hosts[to].s2sout[from] = session; -- luacheck: ignore 122
		end
		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);
			local send = session.sends2s;
			for i, data in ipairs(sendq) do
				send(data[1]);
				sendq[i] = nil;
			end
			session.sendq = nil;
		end
	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")
			}, nil, "Could not establish encrypted connection to remote server");
		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";
	elseif session.type ~= "s2sin" and session.type ~= "s2sout" then
		return false;
	end

	if session.incoming and host then
		if not session.hosts[host] then session.hosts[host] = {}; end
		session.hosts[host].authed = true;
	end
	session.log("debug", "connection %s->%s is now authenticated for %s", session.from_host, session.to_host, host);

	if (session.type == "s2sout" and session.external_auth ~= "succeeded") or session.type == "s2sin" then
		-- Stream either used dialback for authentication or is an incoming stream.
		mark_connected(session);
	end

	return true;
end

--- Helper to check that a session peer's certificate is valid
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

	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" };

function stream_callbacks.handlestanza(session, stanza)
	stanza = session.filter("stanzas/in", stanza);
	session.thread:run(stanza);
end

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

function stream_callbacks.streamopened(session, attr)
	-- run _streamopened in async context
	session.thread:run({ attr = attr });
end

function stream_callbacks._streamopened(session, attr)
	session.version = tonumber(attr.version) or 0;
	session.had_stream = true; -- Had a stream opened at least once

	-- TODO: Rename session.secure to session.encrypted
	if session.secure == false then
		session.secure = true;
		session.encrypted = true;

		local sock = session.conn:socket();
		if sock.info then
			local info = sock:info();
			(session.log or log)("info", "Stream encrypted (%s with %s)", info.protocol, info.cipher);
			session.compressed = info.compression;
		else
			(session.log or log)("info", "Stream encrypted");
		end
	end

	if session.direction == "incoming" then
		-- Send a reply stream header

		-- Validate to/from
		local to, from = attr.to, attr.from;
		if to then to = nameprep(attr.to); end
		if from then from = nameprep(attr.from); end
		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)
		session.notopen = nil;
		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");
				fire_global_event("s2s-stream-features-legacy", { origin = session, features = features });
			end

			if ( session.type == "s2sin" or session.type == "s2sout" ) or features.tags[1] then
				log("debug", "Sending stream features: %s", features);
				session.sends2s(features);
			else
				(session.log or log)("warn", "No stream features to offer, giving up");
				session:close({ condition = "undefined-condition", text = "No stream features to offer" });
			end
		end
	elseif session.direction == "outgoing" then
		session.notopen = nil;
		if not attr.id then
			log("warn", "Stream response did not give us a stream id!");
			session:close({ condition = "undefined-condition", text = "Missing stream ID" });
			return;
		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.log("debug", "Invalid opening stream header (%s)", (data:gsub("^([^\1]+)\1", "{%1}")));
		session:close("invalid-namespace");
	elseif error == "parse-error" then
		session.log("debug", "Server-to-server XML parse error: %s", error);
		session:close("not-well-formed");
	elseif error == "stream-error" then
		local condition, text = "undefined-condition";
		for child in data:childtags(nil, xmlns_xmpp_streams) do
			if child.name ~= "text" then
				condition = child.name;
			else
				text = child:get_text();
			end
			if condition ~= "undefined-condition" and text then
				break;
			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

--- Session methods
local stream_xmlns_attr = {xmlns='urn:ietf:params:xml:ns:xmpp-streams'};
local function session_close(session, reason, remote_reason, bounce_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, 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, reason);
					session.sends2s(reason);
				end
			end
		end

		session.sends2s("</stream:stream>");
		function session.sends2s() return false; end

		-- luacheck: ignore 422/reason
		-- FIXME reason should be managed in a place common to c2s, s2s, bosh, component etc
		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:gsub("^.", string.upper),
			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.incoming 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, bounce_reason);
					conn:close();
				end
			end);
		else
			s2s_destroy_session(session, reason, bounce_reason);
			conn:close(); -- Close immediately, as this is an outgoing connection or is not authed
		end
	end
end

function session_stream_attrs(session, from, to, attr) -- luacheck: ignore 212/session
	if not from or (hosts[from] and hosts[from].modules.dialback) then
		attr["xmlns:db"] = 'jabber:server:dialback';
	end
	if not from then
		attr.from = '';
	end
	if not to then
		attr.to = '';
	end
end

-- Session initialization logic shared by incoming and outgoing
local function initialize_session(session)
	local stream = new_xmpp_stream(session, stream_callbacks);

	session.thread = runner(function (stanza)
		if stanza.name == nil then
			stream_callbacks._streamopened(session, stanza.attr);
		else
			core_process_stanza(session, stanza);
		end
	end, runner_callbacks, session);

	local log = session.log or log;
	session.stream = stream;

	session.notopen = true;

	function session.reset_stream()
		session.notopen = true;
		session.streamid = nil;
		session.stream:reset();
	end

	session.stream_attrs = session_stream_attrs;

	local filter = initialize_filters(session);
	local conn = session.conn;
	local w = conn.write;

	function session.sends2s(t)
		log("debug", "Sending[%s]: %s", session.type, 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

	function session.data(data)
		data = filter("bytes/in", data);
		if data then
			local ok, err = stream:feed(data);
			if ok then return; end
			log("debug", "Received invalid XML (%s) %d bytes: %q", err, #data, data:sub(1, 300));
			session:close("not-well-formed", nil, "Received invalid XML from remote server");
		end
	end

	session.close = session_close;

	local handlestanza = stream_callbacks.handlestanza;
	function session.dispatch_stanza(session, stanza) -- luacheck: ignore 432/session
		return handlestanza(session, stanza);
	end

	module:fire_event("s2s-created", { session = session });

	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 runner_callbacks:ready()
	self.data.log("debug", "Runner %s ready (%s)", self.thread, coroutine.status(self.thread));
	self.data.conn:resume();
end

function runner_callbacks:waiting()
	self.data.log("debug", "Runner %s waiting (%s)", self.thread, coroutine.status(self.thread));
	self.data.conn:pause();
end

function runner_callbacks:error(err)
	(self.data.log or log)("error", "Traceback[s2s]: %s", err);
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");
		initialize_session(session);
	else -- Outgoing session connected
		session:open_stream(session.from_host, session.to_host);
	end
	session.ip = conn:ip();
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;
		(session.log or log)("debug", "s2s disconnected: %s->%s (%s)", session.from_host, session.to_host, err or "connection closed");
		s2s_destroy_session(session, err);
	end
end

function listener.onfail(data, err)
	local session = data and data.session;
	if session then
		if err and session.direction == "outgoing" and session.notopen then
			(session.log or log)("debug", "s2s connection attempt failed: %s", err);
		end
		(session.log or log)("debug", "s2s disconnected: %s->%s (%s)", session.from_host, session.to_host, err or "connection closed");
		s2s_destroy_session(session, err);
	end
end

function listener.onreadtimeout(conn)
	local session = sessions[conn];
	if session then
		local host = session.host or session.to_host;
		return (hosts[host] or prosody).events.fire_event("s2s-read-timeout", { session = session });
	end
end

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

function listener.ondetach(conn)
	sessions[conn] = nil;
end

function listener.onattach(conn, data)
	local session = data and data.session;
	if session then
		session.conn = conn;
		sessions[conn] = session;
		initialize_session(session);
	end
end

-- Complete the sentence "Your certificate " with what's wrong
local function friendly_cert_error(session) --> string
	if session.cert_chain_status == "invalid" then
		if session.cert_chain_errors then
			local cert_errors = set.new(session.cert_chain_errors[1]);
			if cert_errors:contains("certificate has expired") then
				return "has expired";
			elseif cert_errors:contains("self signed certificate") then
				return "is self-signed";
			end
		end
		return "is not trusted"; -- for some other reason
	elseif session.cert_identity_status == "invalid" then
		return "is not valid for this name";
	end
	-- this should normally be unreachable except if no s2s auth module was loaded
	return "could not be validated";
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)");
		local reason = friendly_cert_error(session);
		-- XEP-0178 recommends closing outgoing connections without warning
		-- but does not give a rationale for this.
		-- In practice most cases are configuration mistakes or forgotten
		-- certificate renewals. We think it's better to let the other party
		-- know about the problem so that they can fix it.
		session:close({ condition = "not-authorized", text = "Your server's certificate "..reason },
			nil, "Remote server's certificate "..reason);
		return false;
	end
end

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

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, -200);



module:provides("net", {
	name = "s2s";
	listener = listener;
	default_port = 5269;
	encryption = "starttls";
	ssl_config = { -- FIXME This is not used atm, see mod_tls
		verify = { "peer", "client_once", };
	};
	multiplex = {
		pattern = "^<.*:stream.*%sxmlns%s*=%s*(['\"])jabber:server%1.*>";
	};
});