-- 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 rfc6724_dest = require "util.rfc6724".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 local_addresses = require "util.net".local_addresses; 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 function s2sout.initiate_connection(host_session) initialize_filters(host_session); host_session.version = 1; -- 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 and #answer > 0 then log("debug", "%s has SRV records, handling...", to_host); local srv_hosts = { answer = answer }; 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", "%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", 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 have_other_result = not(has_ipv4) or not(has_ipv6) or 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 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 = 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 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 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; -- Reset secure flag in case this is another -- connection attempt after a failed STARTTLS host_session.secure = 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, "*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 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 end); return s2sout;