s2smanager, mod_s2s, mod_s2s/s2sout: Split connection handling out of s2smanager into mod_s2s, and further split connection logic for s2sout to a module lib, s2sout.lib.lua

1 files changed, 314 insertions, 0 deletions

diff --git a/plugins/s2s/s2sout.lib.lua b/plugins/s2s/s2sout.lib.lua
new file mode 100644
index 00000000..094126e7
--- /dev/null
+++ b/plugins/s2s/s2sout.lib.lua
@@ -0,0 +1,314 @@
+-- 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 initialize_filters = require "util.filters".initialize;
+local idna_to_ascii = require "util.encodings".idna.to_ascii;
+local add_task = require "util.timer".add_task;
+local socket = require "socket";
+
+local s2s_destroy_session = require "core.s2smanager".destroy_session;
+
+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);
+	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", 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");
+			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 not sources then
+			sources =  {};
+			for i, source in ipairs(cfg_sources) do
+				if source == "*" then
+					sources[i] = new_ip("0.0.0.0", "IPv4");
+				else
+					sources[i] = new_ip(source, (source:find(":") and "IPv6") or "IPv4");
+				end
+			end
+		end
+
+		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");
+
+		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");
+
+		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
+		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);
+	
+	host_session:open_stream(from_host, to_host);
+	
+	log("debug", "Connection attempt in progress...");
+	return true;
+end
+
+return s2sout;