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