plugins/mod_s2s/s2sout.lib.lua

   1 -- Prosody IM
   2 -- Copyright (C) 2008-2010 Matthew Wild
   3 -- Copyright (C) 2008-2010 Waqas Hussain
   4 --
   5 -- This project is MIT/X11 licensed. Please see the
   6 -- COPYING file in the source package for more information.
   7 --
   8
   9 --- Module containing all the logic for connecting to a remote server
  10
  11 local portmanager = require "core.portmanager";
  12 local wrapclient = require "net.server".wrapclient;
  13 local initialize_filters = require "util.filters".initialize;
  14 local idna_to_ascii = require "util.encodings".idna.to_ascii;
  15 local new_ip = require "util.ip".new_ip;
  16 local rfc3484_dest = require "util.rfc3484".destination;
  17 local socket = require "socket";
  18 local adns = require "net.adns";
  19 local dns = require "net.dns";
  20 local t_insert, t_sort, ipairs = table.insert, table.sort, ipairs;
  21 local st = require "util.stanza";
  22
  23 local s2s_destroy_session = require "core.s2smanager".destroy_session;
  24
  25 local log = module._log;
  26
  27 local sources = {};
  28 local has_ipv4, has_ipv6;
  29
  30 local dns_timeout = module:get_option_number("dns_timeout", 15);
  31 dns.settimeout(dns_timeout);
  32 local max_dns_depth = module:get_option_number("dns_max_depth", 3);
  33
  34 local s2sout = {};
  35
  36 local s2s_listener;
  37
  38
  39 function s2sout.set_listener(listener)
  40         s2s_listener = listener;
  41 end
  42
  43 local function compare_srv_priorities(a,b)
  44         return a.priority < b.priority or (a.priority == b.priority and a.weight > b.weight);
  45 end
  46
  47 local function session_open_stream(session, from, to)
  48         session.sends2s(st.stanza("stream:stream", {
  49                 xmlns='jabber:server', ["xmlns:db"]='jabber:server:dialback',
  50                 ["xmlns:stream"]='http://etherx.jabber.org/streams',
  51                 from=from, to=to, version='1.0', ["xml:lang"]='en'}):top_tag());
  52 end
  53
  54 function s2sout.initiate_connection(host_session)
  55         initialize_filters(host_session);
  56         host_session.open_stream = session_open_stream;
  57
  58         -- Kick the connection attempting machine into life
  59         if not s2sout.attempt_connection(host_session) then
  60                 -- Intentionally not returning here, the
  61                 -- session is needed, connected or not
  62                 s2s_destroy_session(host_session);
  63         end
  64
  65         if not host_session.sends2s then
  66                 -- A sends2s which buffers data (until the stream is opened)
  67                 -- note that data in this buffer will be sent before the stream is authed
  68                 -- and will not be ack'd in any way, successful or otherwise
  69                 local buffer;
  70                 function host_session.sends2s(data)
  71                         if not buffer then
  72                                 buffer = {};
  73                                 host_session.send_buffer = buffer;
  74                         end
  75                         log("debug", "Buffering data on unconnected s2sout to %s", tostring(host_session.to_host));
  76                         buffer[#buffer+1] = data;
  77                         log("debug", "Buffered item %d: %s", #buffer, tostring(data));
  78                 end
  79         end
  80 end
  81
  82 function s2sout.attempt_connection(host_session, err)
  83         local from_host, to_host = host_session.from_host, host_session.to_host;
  84         local connect_host, connect_port = to_host and idna_to_ascii(to_host), 5269;
  85
  86         if not connect_host then
  87                 return false;
  88         end
  89
  90         if not err then -- This is our first attempt
  91                 log("debug", "First attempt to connect to %s, starting with SRV lookup...", to_host);
  92                 host_session.connecting = true;
  93                 local handle;
  94                 handle = adns.lookup(function (answer)
  95                         handle = nil;
  96                         host_session.connecting = nil;
  97                         if answer and #answer > 0 then
  98                                 log("debug", "%s has SRV records, handling...", to_host);
  99                                 local srv_hosts = {};
 100                                 host_session.srv_hosts = srv_hosts;
 101                                 for _, record in ipairs(answer) do
 102                                         t_insert(srv_hosts, record.srv);
 103                                 end
 104                                 if #srv_hosts == 1 and srv_hosts[1].target == "." then
 105                                         log("debug", "%s does not provide a XMPP service", to_host);
 106                                         s2s_destroy_session(host_session, err); -- Nothing to see here
 107                                         return;
 108                                 end
 109                                 t_sort(srv_hosts, compare_srv_priorities);
 110
 111                                 local srv_choice = srv_hosts[1];
 112                                 host_session.srv_choice = 1;
 113                                 if srv_choice then
 114                                         connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
 115                                         log("debug", "Best record found, will connect to %s:%d", connect_host, connect_port);
 116                                 end
 117                         else
 118                                 log("debug", "%s has no SRV records, falling back to A/AAAA", to_host);
 119                         end
 120                         -- Try with SRV, or just the plain hostname if no SRV
 121                         local ok, err = s2sout.try_connect(host_session, connect_host, connect_port);
 122                         if not ok then
 123                                 if not s2sout.attempt_connection(host_session, err) then
 124                                         -- No more attempts will be made
 125                                         s2s_destroy_session(host_session, err);
 126                                 end
 127                         end
 128                 end, "_xmpp-server._tcp."..connect_host..".", "SRV");
 129
 130                 return true; -- Attempt in progress
 131         elseif host_session.ip_hosts then
 132                 return s2sout.try_connect(host_session, connect_host, connect_port, err);
 133         elseif host_session.srv_hosts and #host_session.srv_hosts > host_session.srv_choice then -- Not our first attempt, and we also have SRV
 134                 host_session.srv_choice = host_session.srv_choice + 1;
 135                 local srv_choice = host_session.srv_hosts[host_session.srv_choice];
 136                 connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
 137                 host_session.log("info", "Connection failed (%s). Attempt #%d: This time to %s:%d", tostring(err), host_session.srv_choice, connect_host, connect_port);
 138         else
 139                 host_session.log("info", "Out of connection options, can't connect to %s", tostring(host_session.to_host));
 140                 -- We're out of options
 141                 return false;
 142         end
 143
 144         if not (connect_host and connect_port) then
 145                 -- Likely we couldn't resolve DNS
 146                 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));
 147                 return false;
 148         end
 149
 150         return s2sout.try_connect(host_session, connect_host, connect_port);
 151 end
 152
 153 function s2sout.try_next_ip(host_session)
 154         host_session.connecting = nil;
 155         host_session.ip_choice = host_session.ip_choice + 1;
 156         local ip = host_session.ip_hosts[host_session.ip_choice];
 157         local ok, err= s2sout.make_connect(host_session, ip.ip, ip.port);
 158         if not ok then
 159                 if not s2sout.attempt_connection(host_session, err or "closed") then
 160                         err = err and (": "..err) or "";
 161                         s2s_destroy_session(host_session, "Connection failed"..err);
 162                 end
 163         end
 164 end
 165
 166 function s2sout.try_connect(host_session, connect_host, connect_port, err)
 167         host_session.connecting = true;
 168
 169         if not err then
 170                 local IPs = {};
 171                 host_session.ip_hosts = IPs;
 172                 local handle4, handle6;
 173                 local have_other_result = not(has_ipv4) or not(has_ipv6) or false;
 174
 175                 if has_ipv4 then
 176                         handle4 = adns.lookup(function (reply, err)
 177                                 handle4 = nil;
 178
 179                                 -- COMPAT: This is a compromise for all you CNAME-(ab)users :)
 180                                 if not (reply and reply[#reply] and reply[#reply].a) then
 181                                         local count = max_dns_depth;
 182                                         reply = dns.peek(connect_host, "CNAME", "IN");
 183                                         while count > 0 and reply and reply[#reply] and not reply[#reply].a and reply[#reply].cname do
 184                                                 log("debug", "Looking up %s (DNS depth is %d)", tostring(reply[#reply].cname), count);
 185                                                 reply = dns.peek(reply[#reply].cname, "A", "IN") or dns.peek(reply[#reply].cname, "CNAME", "IN");
 186                                                 count = count - 1;
 187                                         end
 188                                 end
 189                                 -- end of CNAME resolving
 190
 191                                 if reply and reply[#reply] and reply[#reply].a then
 192                                         for _, ip in ipairs(reply) do
 193                                                 log("debug", "DNS reply for %s gives us %s", connect_host, ip.a);
 194                                                 IPs[#IPs+1] = new_ip(ip.a, "IPv4");
 195                                         end
 196                                 end
 197
 198                                 if have_other_result then
 199                                         if #IPs > 0 then
 200                                                 rfc3484_dest(host_session.ip_hosts, sources);
 201                                                 for i = 1, #IPs do
 202                                                         IPs[i] = {ip = IPs[i], port = connect_port};
 203                                                 end
 204                                                 host_session.ip_choice = 0;
 205                                                 s2sout.try_next_ip(host_session);
 206                                         else
 207                                                 log("debug", "DNS lookup failed to get a response for %s", connect_host);
 208                                                 host_session.ip_hosts = nil;
 209                                                 if not s2sout.attempt_connection(host_session, "name resolution failed") then -- Retry if we can
 210                                                         log("debug", "No other records to try for %s - destroying", host_session.to_host);
 211                                                         err = err and (": "..err) or "";
 212                                                         s2s_destroy_session(host_session, "DNS resolution failed"..err); -- End of the line, we can't
 213                                                 end
 214                                         end
 215                                 else
 216                                         have_other_result = true;
 217                                 end
 218                         end, connect_host, "A", "IN");
 219                 else
 220                         have_other_result = true;
 221                 end
 222
 223                 if has_ipv6 then
 224                         handle6 = adns.lookup(function (reply, err)
 225                                 handle6 = nil;
 226
 227                                 if reply and reply[#reply] and reply[#reply].aaaa then
 228                                         for _, ip in ipairs(reply) do
 229                                                 log("debug", "DNS reply for %s gives us %s", connect_host, ip.aaaa);
 230                                                 IPs[#IPs+1] = new_ip(ip.aaaa, "IPv6");
 231                                         end
 232                                 end
 233
 234                                 if have_other_result then
 235                                         if #IPs > 0 then
 236                                                 rfc3484_dest(host_session.ip_hosts, sources);
 237                                                 for i = 1, #IPs do
 238                                                         IPs[i] = {ip = IPs[i], port = connect_port};
 239                                                 end
 240                                                 host_session.ip_choice = 0;
 241                                                 s2sout.try_next_ip(host_session);
 242                                         else
 243                                                 log("debug", "DNS lookup failed to get a response for %s", connect_host);
 244                                                 host_session.ip_hosts = nil;
 245                                                 if not s2sout.attempt_connection(host_session, "name resolution failed") then -- Retry if we can
 246                                                         log("debug", "No other records to try for %s - destroying", host_session.to_host);
 247                                                         err = err and (": "..err) or "";
 248                                                         s2s_destroy_session(host_session, "DNS resolution failed"..err); -- End of the line, we can't
 249                                                 end
 250                                         end
 251                                 else
 252                                         have_other_result = true;
 253                                 end
 254                         end, connect_host, "AAAA", "IN");
 255                 else
 256                         have_other_result = true;
 257                 end
 258                 return true;
 259         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
 260                 s2sout.try_next_ip(host_session);
 261         else
 262                 host_session.ip_hosts = nil;
 263                 if not s2sout.attempt_connection(host_session, "out of IP addresses") then -- Retry if we can
 264                         log("debug", "No other records to try for %s - destroying", host_session.to_host);
 265                         err = err and (": "..err) or "";
 266                         s2s_destroy_session(host_session, "Connecting failed"..err); -- End of the line, we can't
 267                         return false;
 268                 end
 269         end
 270
 271         return true;
 272 end
 273
 274 function s2sout.make_connect(host_session, connect_host, connect_port)
 275         (host_session.log or log)("info", "Beginning new connection attempt to %s ([%s]:%d)", host_session.to_host, connect_host.addr, connect_port);
 276         -- Ok, we're going to try to connect
 277
 278         local from_host, to_host = host_session.from_host, host_session.to_host;
 279
 280         local conn, handler;
 281         if connect_host.proto == "IPv4" then
 282                 conn, handler = socket.tcp();
 283         else
 284                 conn, handler = socket.tcp6();
 285         end
 286
 287         if not conn then
 288                 log("warn", "Failed to create outgoing connection, system error: %s", handler);
 289                 return false, handler;
 290         end
 291
 292         conn:settimeout(0);
 293         local success, err = conn:connect(connect_host.addr, connect_port);
 294         if not success and err ~= "timeout" then
 295                 log("warn", "s2s connect() to %s (%s:%d) failed: %s", host_session.to_host, connect_host.addr, connect_port, err);
 296                 return false, err;
 297         end
 298
 299         conn = wrapclient(conn, connect_host.addr, connect_port, s2s_listener, "*a");
 300         host_session.conn = conn;
 301
 302         local filter = initialize_filters(host_session);
 303         local w, log = conn.write, host_session.log;
 304         host_session.sends2s = function (t)
 305                 log("debug", "sending: %s", (t.top_tag and t:top_tag()) or t:match("^[^>]*>?"));
 306                 if t.name then
 307                         t = filter("stanzas/out", t);
 308                 end
 309                 if t then
 310                         t = filter("bytes/out", tostring(t));
 311                         if t then
 312                                 return w(conn, tostring(t));
 313                         end
 314                 end
 315         end
 316
 317         -- Register this outgoing connection so that xmppserver_listener knows about it
 318         -- otherwise it will assume it is a new incoming connection
 319         s2s_listener.register_outgoing(conn, host_session);
 320
 321         log("debug", "Connection attempt in progress...");
 322         return true;
 323 end
 324
 325 module:hook_global("service-added", function (event)
 326         if event.name ~= "s2s" then return end
 327
 328         local s2s_sources = portmanager.get_active_services():get("s2s");
 329         if not s2s_sources then
 330                 module:log("warn", "s2s not listening on any ports, outgoing connections may fail");
 331                 return;
 332         end
 333         for source, _ in pairs(s2s_sources) do
 334                 if source == "*" or source == "0.0.0.0" then
 335                         if not socket.local_addresses then
 336                                 sources[#sources + 1] = new_ip("0.0.0.0", "IPv4");
 337                         else
 338                                 for _, addr in ipairs(socket.local_addresses("ipv4", true)) do
 339                                         sources[#sources + 1] = new_ip(addr, "IPv4");
 340                                 end
 341                         end
 342                 elseif source == "::" then
 343                         if not socket.local_addresses then
 344                                 sources[#sources + 1] = new_ip("::", "IPv6");
 345                         else
 346                                 for _, addr in ipairs(socket.local_addresses("ipv6", true)) do
 347                                         sources[#sources + 1] = new_ip(addr, "IPv6");
 348                                 end
 349                         end
 350                 else
 351                         sources[#sources + 1] = new_ip(source, (source:find(":") and "IPv6") or "IPv4");
 352                 end
 353         end
 354         for i = 1,#sources do
 355                 if sources[i].proto == "IPv6" then
 356                         has_ipv6 = true;
 357                 elseif sources[i].proto == "IPv4" then
 358                         has_ipv4 = true;
 359                 end
 360         end
 361 end);
 362
 363 return s2sout;