--- a/plugins/mod_s2s/mod_s2s.lua	Sat Aug 10 16:01:42 2019 +0200
+++ b/plugins/mod_s2s/mod_s2s.lua	Sat Nov 10 13:37:32 2018 +0100
@@ -27,8 +27,8 @@
 local uuid_gen = require "util.uuid".generate;
 local fire_global_event = prosody.events.fire_event;
 local runner = require "util.async".runner;
-
-local s2sout = module:require("s2sout");
+local connect = require "net.connect".connect;
+local service = require "net.resolvers.service";
 
 local connect_timeout = module:get_option_number("s2s_timeout", 90);
 local stream_close_timeout = module:get_option_number("s2s_close_timeout", 5);
@@ -45,6 +45,8 @@
 
 local runner_callbacks = {};
 
+local listener = {};
+
 local log = module._log;
 
 module:hook("stats-update", function ()
@@ -154,17 +156,13 @@
 	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);
-	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
+	connect(service.new(to_host, "xmpp-server", "tcp", { default_port = 5269 }), listener, nil, { session = host_session });
 	return true;
 end
 
@@ -479,8 +477,6 @@
 	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)
@@ -679,11 +675,16 @@
 	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);
-			if s2sout.attempt_connection(session, err) then
-				return; -- Session lives for now
-			end
 		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);
@@ -707,6 +708,15 @@
 	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
+
 function check_auth_policy(event)
 	local host, session = event.host, event.session;
 	local must_secure = secure_auth;
@@ -730,8 +740,6 @@
 
 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

--- a/plugins/mod_s2s/s2sout.lib.lua	Sat Aug 10 16:01:42 2019 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,349 +0,0 @@
--- 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
-
--- luacheck: ignore 432/err
-
-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 rfc6724_dest = require "util.rfc6724".destination;
-local socket = require "socket";
-local adns = require "net.adns";
-local t_insert, t_sort, ipairs = table.insert, table.sort, ipairs;
-local local_addresses = require "util.net".local_addresses;
-
-local s2s_destroy_session = require "core.s2smanager".destroy_session;
-
-local default_mode = module:get_option("network_default_read_size", 4096);
-
-local log = module._log;
-
-local sources = {};
-local has_ipv4, has_ipv6;
-
-local dns_timeout = module:get_option_number("dns_timeout", 15);
-local resolvers = module:get_option_set("s2s_dns_resolvers")
-
-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
-
-function s2sout.initiate_connection(host_session)
-	local log = host_session.log or log;
-
-	initialize_filters(host_session);
-	host_session.version = 1;
-
-	host_session.resolver = adns.resolver();
-	host_session.resolver._resolver:settimeout(dns_timeout);
-	if resolvers then
-		for resolver in resolvers do
-			host_session.resolver._resolver:addnameserver(resolver);
-		end
-	end
-
-	-- 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", host_session.to_host);
-			buffer[#buffer+1] = data;
-			log("debug", "Buffered item %d: %s", #buffer, data);
-		end
-	end
-end
-
-function s2sout.attempt_connection(host_session, err)
-	local to_host = host_session.to_host;
-	local connect_host, connect_port = to_host and idna_to_ascii(to_host), 5269;
-	local log = host_session.log or log;
-
-	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;
-		host_session.resolver:lookup(function (answer)
-			local srv_hosts = { answer = answer };
-			host_session.srv_hosts = srv_hosts;
-			host_session.srv_choice = 0;
-			host_session.connecting = nil;
-			if answer and #answer > 0 then
-				log("debug", "%s has SRV records, handling...", to_host);
-				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", "%s does not provide a XMPP service", to_host);
-					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", "%s has no SRV records, falling back to A/AAAA", to_host);
-			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", err, host_session.srv_choice, connect_host, connect_port);
-	else
-		host_session.log("info", "Failed in all attempts to connect to %s", 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 :(", connect_host, connect_port, 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;
-	local log = host_session.log or log;
-
-	if not err then
-		local IPs = {};
-		host_session.ip_hosts = IPs;
-		-- luacheck: ignore 231/handle4 231/handle6
-		local handle4, handle6;
-		local have_other_result = not(has_ipv4) or not(has_ipv6) or false;
-
-		if has_ipv4 then
-			handle4 = host_session.resolver:lookup(function (reply, err)
-				handle4 = nil;
-
-				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
-				elseif err then
-					log("debug", "Error in DNS lookup: %s", err);
-				end
-
-				if have_other_result then
-					if #IPs > 0 then
-						rfc6724_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
-					have_other_result = true;
-				end
-			end, connect_host, "A", "IN");
-		else
-			have_other_result = true;
-		end
-
-		if has_ipv6 then
-			handle6 = host_session.resolver: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
-				elseif err then
-					log("debug", "Error in DNS lookup: %s", err);
-				end
-
-				if have_other_result then
-					if #IPs > 0 then
-						rfc6724_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
-					have_other_result = true;
-				end
-			end, connect_host, "AAAA", "IN");
-		else
-			have_other_result = 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
-		log("debug", "Out of IP addresses, trying next SRV record (if any)");
-		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)
-	local log = host_session.log or log;
-	log("debug", "Beginning new connection attempt to %s ([%s]:%d)", host_session.to_host, connect_host.addr, connect_port);
-
-	-- Reset secure flag in case this is another
-	-- connection attempt after a failed STARTTLS
-	host_session.secure = nil;
-	host_session.encrypted = nil;
-
-	local conn, handler;
-	local proto = connect_host.proto;
-	if proto == "IPv4" then
-		conn, handler = socket.tcp();
-	elseif proto == "IPv6" and socket.tcp6 then
-		conn, handler = socket.tcp6();
-	else
-		handler = "Unsupported protocol: "..tostring(proto);
-	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, default_mode);
-	host_session.conn = conn;
-
-	-- 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_status("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
-			for _, addr in ipairs(local_addresses("ipv4", true)) do
-				sources[#sources + 1] = new_ip(addr, "IPv4");
-			end
-		elseif source == "::" then
-			for _, addr in ipairs(local_addresses("ipv6", true)) do
-				sources[#sources + 1] = new_ip(addr, "IPv6");
-			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
-	if not (has_ipv4 or has_ipv6)  then
-		module:log("warn", "No local IPv4 or IPv6 addresses detected, outgoing connections may fail");
-	end
-end);
-
-return s2sout;