/usr/lib/prosody/modules/mod_s2s/s2sout.lib.lua is in prosody 0.9.1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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-- 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 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 to_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);
-- 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;
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