aboutsummaryrefslogtreecommitdiffstats
path: root/plugins/mod_s2s/s2sout.lib.lua
blob: 3b05b4b962f1963631df680d9d1170aed5596d6d (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
-- 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 containing all the logic for connecting to a remote server

local portmanager = require "core.portmanager";
local wrapclient = require "net.server".wrapclient;
local initialize_filters = require "util.filters".initialize;
local idna_to_ascii = require "util.encodings".idna.to_ascii;
local new_ip = require "util.ip".new_ip;
local rfc3484_dest = require "util.rfc3484".destination;
local socket = require "socket";
local adns = require "net.adns";
local dns = require "net.dns";
local t_insert, t_sort, ipairs = table.insert, table.sort, ipairs;
local st = require "util.stanza";

local s2s_destroy_session = require "core.s2smanager".destroy_session;

local log = module._log;

local sources = {};
local has_ipv4, has_ipv6;

local dns_timeout = module:get_option_number("dns_timeout", 15);
dns.settimeout(dns_timeout);
local max_dns_depth = module:get_option_number("dns_max_depth", 3);

local s2sout = {};

local s2s_listener;


function s2sout.set_listener(listener)
	s2s_listener = listener;
end

local function compare_srv_priorities(a,b)
	return a.priority < b.priority or (a.priority == b.priority and a.weight > b.weight);
end

local function session_open_stream(session, from, to)
	session.sends2s(st.stanza("stream:stream", {
		xmlns='jabber:server', ["xmlns:db"]='jabber:server:dialback',
		["xmlns:stream"]='http://etherx.jabber.org/streams',
		from=from, to=to, version='1.0', ["xml:lang"]='en'}):top_tag());
end

function s2sout.initiate_connection(host_session)
	initialize_filters(host_session);
	host_session.open_stream = session_open_stream;
	
	-- Kick the connection attempting machine into life
	if not s2sout.attempt_connection(host_session) then
		-- Intentionally not returning here, the
		-- session is needed, connected or not
		s2s_destroy_session(host_session);
	end
	
	if not host_session.sends2s then
		-- A sends2s which buffers data (until the stream is opened)
		-- note that data in this buffer will be sent before the stream is authed
		-- and will not be ack'd in any way, successful or otherwise
		local buffer;
		function host_session.sends2s(data)
			if not buffer then
				buffer = {};
				host_session.send_buffer = buffer;
			end
			log("debug", "Buffering data on unconnected s2sout to %s", tostring(host_session.to_host));
			buffer[#buffer+1] = data;
			log("debug", "Buffered item %d: %s", #buffer, tostring(data));
		end
	end
end

function s2sout.attempt_connection(host_session, err)
	local from_host, to_host = host_session.from_host, host_session.to_host;
	local connect_host, connect_port = to_host and idna_to_ascii(to_host), 5269;
	
	if not connect_host then
		return false;
	end
	
	if not err then -- This is our first attempt
		log("debug", "First attempt to connect to %s, starting with SRV lookup...", to_host);
		host_session.connecting = true;
		local handle;
		handle = adns.lookup(function (answer)
			handle = nil;
			host_session.connecting = nil;
			if answer then
				log("debug", to_host.." has SRV records, handling...");
				local srv_hosts = {};
				host_session.srv_hosts = srv_hosts;
				for _, record in ipairs(answer) do
					t_insert(srv_hosts, record.srv);
				end
				if #srv_hosts == 1 and srv_hosts[1].target == "." then
					log("debug", to_host.." does not provide a XMPP service");
					s2s_destroy_session(host_session, err); -- Nothing to see here
					return;
				end
				t_sort(srv_hosts, compare_srv_priorities);
				
				local srv_choice = srv_hosts[1];
				host_session.srv_choice = 1;
				if srv_choice then
					connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
					log("debug", "Best record found, will connect to %s:%d", connect_host, connect_port);
				end
			else
				log("debug", to_host.." has no SRV records, falling back to A/AAAA");
			end
			-- Try with SRV, or just the plain hostname if no SRV
			local ok, err = s2sout.try_connect(host_session, connect_host, connect_port);
			if not ok then
				if not s2sout.attempt_connection(host_session, err) then
					-- No more attempts will be made
					s2s_destroy_session(host_session, err);
				end
			end
		end, "_xmpp-server._tcp."..connect_host..".", "SRV");
		
		return true; -- Attempt in progress
	elseif host_session.ip_hosts then
		return s2sout.try_connect(host_session, connect_host, connect_port, err);
	elseif host_session.srv_hosts and #host_session.srv_hosts > host_session.srv_choice then -- Not our first attempt, and we also have SRV
		host_session.srv_choice = host_session.srv_choice + 1;
		local srv_choice = host_session.srv_hosts[host_session.srv_choice];
		connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
		host_session.log("info", "Connection failed (%s). Attempt #%d: This time to %s:%d", tostring(err), host_session.srv_choice, connect_host, connect_port);
	else
		host_session.log("info", "Out of connection options, can't connect to %s", tostring(host_session.to_host));
		-- We're out of options
		return false;
	end
	
	if not (connect_host and connect_port) then
		-- Likely we couldn't resolve DNS
		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));
		return false;
	end

	return s2sout.try_connect(host_session, connect_host, connect_port);
end

function s2sout.try_next_ip(host_session)
	host_session.connecting = nil;
	host_session.ip_choice = host_session.ip_choice + 1;
	local ip = host_session.ip_hosts[host_session.ip_choice];
	local ok, err= s2sout.make_connect(host_session, ip.ip, ip.port);
	if not ok then
		if not s2sout.attempt_connection(host_session, err or "closed") then
			err = err and (": "..err) or "";
			s2s_destroy_session(host_session, "Connection failed"..err);
		end
	end
end

function s2sout.try_connect(host_session, connect_host, connect_port, err)
	host_session.connecting = true;

	if not err then
		local IPs = {};
		host_session.ip_hosts = IPs;
		local handle4, handle6;
		local has_other = false;

		if has_ipv4 then
		handle4 = adns.lookup(function (reply, err)
			handle4 = nil;

			-- COMPAT: This is a compromise for all you CNAME-(ab)users :)
			if not (reply and reply[#reply] and reply[#reply].a) then
				local count = max_dns_depth;
				reply = dns.peek(connect_host, "CNAME", "IN");
				while count > 0 and reply and reply[#reply] and not reply[#reply].a and reply[#reply].cname do
					log("debug", "Looking up %s (DNS depth is %d)", tostring(reply[#reply].cname), count);
					reply = dns.peek(reply[#reply].cname, "A", "IN") or dns.peek(reply[#reply].cname, "CNAME", "IN");
					count = count - 1;
				end
			end
			-- end of CNAME resolving

			if reply and reply[#reply] and reply[#reply].a then
				for _, ip in ipairs(reply) do
					log("debug", "DNS reply for %s gives us %s", connect_host, ip.a);
					IPs[#IPs+1] = new_ip(ip.a, "IPv4");
				end
			end

			if has_other then
				if #IPs > 0 then
					rfc3484_dest(host_session.ip_hosts, sources);
					for i = 1, #IPs do
						IPs[i] = {ip = IPs[i], port = connect_port};
					end
					host_session.ip_choice = 0;
					s2sout.try_next_ip(host_session);
				else
					log("debug", "DNS lookup failed to get a response for %s", connect_host);
					host_session.ip_hosts = nil;
					if not s2sout.attempt_connection(host_session, "name resolution failed") then -- Retry if we can
						log("debug", "No other records to try for %s - destroying", host_session.to_host);
						err = err and (": "..err) or "";
						s2s_destroy_session(host_session, "DNS resolution failed"..err); -- End of the line, we can't
					end
				end
			else
				has_other = true;
			end
		end, connect_host, "A", "IN");
		else
			has_other = true;
		end

		if has_ipv6 then
		handle6 = adns.lookup(function (reply, err)
			handle6 = nil;

			if reply and reply[#reply] and reply[#reply].aaaa then
				for _, ip in ipairs(reply) do
					log("debug", "DNS reply for %s gives us %s", connect_host, ip.aaaa);
					IPs[#IPs+1] = new_ip(ip.aaaa, "IPv6");
				end
			end

			if has_other then
				if #IPs > 0 then
					rfc3484_dest(host_session.ip_hosts, sources);
					for i = 1, #IPs do
						IPs[i] = {ip = IPs[i], port = connect_port};
					end
					host_session.ip_choice = 0;
					s2sout.try_next_ip(host_session);
				else
					log("debug", "DNS lookup failed to get a response for %s", connect_host);
					host_session.ip_hosts = nil;
					if not s2sout.attempt_connection(host_session, "name resolution failed") then -- Retry if we can
						log("debug", "No other records to try for %s - destroying", host_session.to_host);
						err = err and (": "..err) or "";
						s2s_destroy_session(host_session, "DNS resolution failed"..err); -- End of the line, we can't
					end
				end
			else
				has_other = true;
			end
		end, connect_host, "AAAA", "IN");
		else
			has_other = true;
		end

		return true;
	elseif host_session.ip_hosts and #host_session.ip_hosts > host_session.ip_choice then -- Not our first attempt, and we also have IPs left to try
		s2sout.try_next_ip(host_session);
	else
		host_session.ip_hosts = nil;
		if not s2sout.attempt_connection(host_session, "out of IP addresses") then -- Retry if we can
			log("debug", "No other records to try for %s - destroying", host_session.to_host);
			err = err and (": "..err) or "";
			s2s_destroy_session(host_session, "Connecting failed"..err); -- End of the line, we can't
			return false;
		end
	end

	return true;
end

function s2sout.make_connect(host_session, connect_host, connect_port)
	(host_session.log or log)("info", "Beginning new connection attempt to %s ([%s]:%d)", host_session.to_host, connect_host.addr, connect_port);
	-- Ok, we're going to try to connect
	
	local from_host, to_host = host_session.from_host, host_session.to_host;
	
	local conn, handler;
	if connect_host.proto == "IPv4" then
		conn, handler = socket.tcp();
	else
		if not socket.tcp6 then
			log("warn", "Could not connect to "..to_host..". Your version of lua-socket does not support IPv6");
			return false, "no-ipv6";
		end
		conn, handler = socket.tcp6();
	end
	
	if not conn then
		log("warn", "Failed to create outgoing connection, system error: %s", handler);
		return false, handler;
	end

	conn:settimeout(0);
	local success, err = conn:connect(connect_host.addr, connect_port);
	if not success and err ~= "timeout" then
		log("warn", "s2s connect() to %s (%s:%d) failed: %s", host_session.to_host, connect_host.addr, connect_port, err);
		return false, err;
	end
	
	conn = wrapclient(conn, connect_host.addr, connect_port, s2s_listener, "*a");
	host_session.conn = conn;
	
	local filter = initialize_filters(host_session);
	local w, log = conn.write, host_session.log;
	host_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, tostring(t));
			end
		end
	end
	
	-- Register this outgoing connection so that xmppserver_listener knows about it
	-- otherwise it will assume it is a new incoming connection
	s2s_listener.register_outgoing(conn, host_session);
	
	log("debug", "Connection attempt in progress...");
	return true;
end

module:hook_global("service-added", function (event)
	if event.name ~= "s2s" then return end

	local s2s_sources = portmanager.get_active_services():get("s2s");
	if not s2s_sources then
		module:log("warn", "s2s not listening on any ports, outgoing connections may fail");
		return;
	end
	for source, _ in pairs(s2s_sources) do
		if source == "*" or source == "0.0.0.0" then
			if not socket.local_addresses then
				sources[#sources + 1] = new_ip("0.0.0.0", "IPv4");
			else
				for _, addr in ipairs(socket.local_addresses("ipv4", true)) do
					sources[#sources + 1] = new_ip(addr, "IPv4");
				end
			end
		elseif source == "::" then
			if not socket.local_addresses then
				sources[#sources + 1] = new_ip("::", "IPv6");
			else
				for _, addr in ipairs(socket.local_addresses("ipv6", true)) do
					sources[#sources + 1] = new_ip(addr, "IPv6");
				end
			end
		else
			sources[#sources + 1] = new_ip(source, (source:find(":") and "IPv6") or "IPv4");
		end
	end
	for i = 1,#sources do
		if sources[i].proto == "IPv6" then
			has_ipv6 = true;
		elseif sources[i].proto == "IPv4" then
			has_ipv4 = true;
		end
	end
end);

return s2sout;