core/s2smanager.lua

   1 -- Prosody IM
   2 -- Copyright (C) 2008-2009 Matthew Wild
   3 -- Copyright (C) 2008-2009 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
  10
  11 local hosts = hosts;
  12 local sessions = sessions;
  13 local core_process_stanza = function(a, b) core_process_stanza(a, b); end
  14 local add_task = require "util.timer".add_task;
  15 local socket = require "socket";
  16 local format = string.format;
  17 local t_insert, t_sort = table.insert, table.sort;
  18 local get_traceback = debug.traceback;
  19 local tostring, pairs, ipairs, getmetatable, newproxy, error, tonumber
  20     = tostring, pairs, ipairs, getmetatable, newproxy, error, tonumber;
  21
  22 local idna_to_ascii = require "util.encodings".idna.to_ascii;
  23 local connlisteners_get = require "net.connlisteners".get;
  24 local wrapclient = require "net.server".wrapclient;
  25 local modulemanager = require "core.modulemanager";
  26 local st = require "stanza";
  27 local stanza = st.stanza;
  28 local nameprep = require "util.encodings".stringprep.nameprep;
  29
  30 local fire_event = require "core.eventmanager".fire_event;
  31 local uuid_gen = require "util.uuid".generate;
  32
  33 local logger_init = require "util.logger".init;
  34
  35 local log = logger_init("s2smanager");
  36
  37 local sha256_hash = require "util.hashes".sha256;
  38
  39 local dialback_secret = uuid_gen();
  40
  41 local adns, dns = require "net.adns", require "net.dns";
  42 local config = require "core.configmanager";
  43 local connect_timeout = config.get("*", "core", "s2s_timeout") or 60;
  44 local dns_timeout = config.get("*", "core", "dns_timeout") or 60;
  45 local max_dns_depth = config.get("*", "core", "dns_max_depth") or 3;
  46
  47 incoming_s2s = {};
  48 _G.prosody.incoming_s2s = incoming_s2s;
  49 local incoming_s2s = incoming_s2s;
  50
  51 module "s2smanager"
  52
  53 local function compare_srv_priorities(a,b) return a.priority < b.priority or a.weight < b.weight; end
  54
  55 local function bounce_sendq(session)
  56         local sendq = session.sendq;
  57         if sendq then
  58                 session.log("info", "sending error replies for "..#sendq.." queued stanzas because of failed outgoing connection to "..tostring(session.to_host));
  59                 local dummy = {
  60                         type = "s2sin";
  61                         send = function(s)
  62                                 (session.log or log)("error", "Replying to to an s2s error reply, please report this! Traceback: %s", get_traceback());
  63                         end;
  64                         dummy = true;
  65                 };
  66                 for i, data in ipairs(sendq) do
  67                         local reply = data[2];
  68                         local xmlns = reply.attr.xmlns;
  69                         if not xmlns or xmlns == "jabber:client" or xmlns == "jabber:server" then
  70                                 reply.attr.type = "error";
  71                                 reply:tag("error", {type = "cancel"})
  72                                         :tag("remote-server-not-found", {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"}):up();
  73                                 core_process_stanza(dummy, reply);
  74                         end
  75                         sendq[i] = nil;
  76                 end
  77                 session.sendq = nil;
  78         end
  79 end
  80
  81 function send_to_host(from_host, to_host, data)
  82         local host = hosts[from_host].s2sout[to_host];
  83         if host then
  84                 -- We have a connection to this host already
  85                 if host.type == "s2sout_unauthed" and (data.name ~= "db:verify" or not host.dialback_key) and ((not data.xmlns) or data.xmlns == "jabber:client" or data.xmlns == "jabber:server") then
  86                         (host.log or log)("debug", "trying to send over unauthed s2sout to "..to_host);
  87
  88                         -- Queue stanza until we are able to send it
  89                         if host.sendq then t_insert(host.sendq, {tostring(data), st.reply(data)});
  90                         else host.sendq = { {tostring(data), st.reply(data)} }; end
  91                         host.log("debug", "stanza [%s] queued ", data.name);
  92                 elseif host.type == "local" or host.type == "component" then
  93                         log("error", "Trying to send a stanza to ourselves??")
  94                         log("error", "Traceback: %s", get_traceback());
  95                         log("error", "Stanza: %s", tostring(data));
  96                 else
  97                         (host.log or log)("debug", "going to send stanza to "..to_host.." from "..from_host);
  98                         -- FIXME
  99                         if host.from_host ~= from_host then
 100                                 log("error", "WARNING! This might, possibly, be a bug, but it might not...");
 101                                 log("error", "We are going to send from %s instead of %s", tostring(host.from_host), tostring(from_host));
 102                         end
 103                         host.sends2s(data);
 104                         host.log("debug", "stanza sent over "..host.type);
 105                 end
 106         else
 107                 log("debug", "opening a new outgoing connection for this stanza");
 108                 local host_session = new_outgoing(from_host, to_host);
 109
 110                 -- Store in buffer
 111                 host_session.sendq = { {tostring(data), st.reply(data)} };
 112                 log("debug", "stanza [%s] queued until connection complete", tostring(data.name));
 113                 if (not host_session.connecting) and (not host_session.conn) then
 114                         log("warn", "Connection to %s failed already, destroying session...", to_host);
 115                         destroy_session(host_session);
 116                 end
 117         end
 118 end
 119
 120 local open_sessions = 0;
 121
 122 function new_incoming(conn)
 123         local session = { conn = conn, type = "s2sin_unauthed", direction = "incoming", hosts = {} };
 124         if true then
 125                 session.trace = newproxy(true);
 126                 getmetatable(session.trace).__gc = function () open_sessions = open_sessions - 1; end;
 127         end
 128         open_sessions = open_sessions + 1;
 129         local w, log = conn.write, logger_init("s2sin"..tostring(conn):match("[a-f0-9]+$"));
 130         session.log = log;
 131         session.sends2s = function (t) log("debug", "sending: %s", (t.top_tag and t:top_tag()) or t:match("^([^>]*>?)")); w(tostring(t)); end
 132         incoming_s2s[session] = true;
 133         add_task(connect_timeout, function ()
 134                 if session.conn ~= conn or
 135                    session.type == "s2sin" then
 136                         return; -- Ok, we're connect[ed|ing]
 137                 end
 138                 -- Not connected, need to close session and clean up
 139                 (session.log or log)("warn", "Destroying incomplete session %s->%s due to inactivity",
 140                     session.from_host or "(unknown)", session.to_host or "(unknown)");
 141                 session:close("connection-timeout");
 142         end);
 143         return session;
 144 end
 145
 146 function new_outgoing(from_host, to_host)
 147                 local host_session = { to_host = to_host, from_host = from_host, host = from_host,
 148                                        notopen = true, type = "s2sout_unauthed", direction = "outgoing" };
 149
 150                 hosts[from_host].s2sout[to_host] = host_session;
 151
 152                 local log;
 153                 do
 154                         local conn_name = "s2sout"..tostring(host_session):match("[a-f0-9]*$");
 155                         log = logger_init(conn_name);
 156                         host_session.log = log;
 157                 end
 158
 159                 -- Kick the connection attempting machine
 160                 attempt_connection(host_session);
 161
 162                 if not host_session.sends2s then
 163                         -- A sends2s which buffers data (until the stream is opened)
 164                         -- note that data in this buffer will be sent before the stream is authed
 165                         -- and will not be ack'd in any way, successful or otherwise
 166                         local buffer;
 167                         function host_session.sends2s(data)
 168                                 if not buffer then
 169                                         buffer = {};
 170                                         host_session.send_buffer = buffer;
 171                                 end
 172                                 log("debug", "Buffering data on unconnected s2sout to %s", to_host);
 173                                 buffer[#buffer+1] = data;
 174                                 log("debug", "Buffered item %d: %s", #buffer, tostring(data));
 175                         end
 176
 177                 end
 178
 179                 return host_session;
 180 end
 181
 182
 183 function attempt_connection(host_session, err)
 184         local from_host, to_host = host_session.from_host, host_session.to_host;
 185         local connect_host, connect_port = idna_to_ascii(to_host), 5269;
 186
 187         if not connect_host then
 188                 return false;
 189         end
 190
 191         if not err then -- This is our first attempt
 192                 log("debug", "First attempt to connect to %s, starting with SRV lookup...", to_host);
 193                 host_session.connecting = true;
 194                 local handle;
 195                 handle = adns.lookup(function (answer)
 196                         handle = nil;
 197                         host_session.connecting = nil;
 198                         if answer then
 199                                 log("debug", to_host.." has SRV records, handling...");
 200                                 local srv_hosts = {};
 201                                 host_session.srv_hosts = srv_hosts;
 202                                 for _, record in ipairs(answer) do
 203                                         t_insert(srv_hosts, record.srv);
 204                                 end
 205                                 t_sort(srv_hosts, compare_srv_priorities);
 206
 207                                 local srv_choice = srv_hosts[1];
 208                                 host_session.srv_choice = 1;
 209                                 if srv_choice then
 210                                         connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
 211                                         log("debug", "Best record found, will connect to %s:%d", connect_host, connect_port);
 212                                 end
 213                         else
 214                                 log("debug", to_host.." has no SRV records, falling back to A");
 215                         end
 216                         -- Try with SRV, or just the plain hostname if no SRV
 217                         local ok, err = try_connect(host_session, connect_host, connect_port);
 218                         if not ok then
 219                                 if not attempt_connection(host_session, err) then
 220                                         -- No more attempts will be made
 221                                         destroy_session(host_session);
 222                                 end
 223                         end
 224                 end, "_xmpp-server._tcp."..connect_host..".", "SRV");
 225
 226                 -- Set handler for DNS timeout
 227                 add_task(dns_timeout, function ()
 228                         if handle then
 229                                 adns.cancel(handle, true);
 230                         end
 231                 end);
 232
 233                 log("debug", "DNS lookup for %s sent, waiting for response before we can connect", to_host);
 234                 return true; -- Attempt in progress
 235         elseif host_session.srv_hosts and #host_session.srv_hosts > host_session.srv_choice then -- Not our first attempt, and we also have SRV
 236                 host_session.srv_choice = host_session.srv_choice + 1;
 237                 local srv_choice = host_session.srv_hosts[host_session.srv_choice];
 238                 connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
 239                 host_session.log("info", "Connection failed (%s). Attempt #%d: This time to %s:%d", tostring(err), host_session.srv_choice, connect_host, connect_port);
 240         else
 241                 host_session.log("info", "Out of connection options, can't connect to %s", tostring(host_session.to_host));
 242                 -- We're out of options
 243                 return false;
 244         end
 245
 246         if not (connect_host and connect_port) then
 247                 -- Likely we couldn't resolve DNS
 248                 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));
 249                 return false;
 250         end
 251
 252         return try_connect(host_session, connect_host, connect_port);
 253 end
 254
 255 function try_connect(host_session, connect_host, connect_port)
 256         host_session.connecting = true;
 257         local handle;
 258         handle = adns.lookup(function (reply)
 259                 handle = nil;
 260                 host_session.connecting = nil;
 261
 262                 -- COMPAT: This is a compromise for all you CNAME-(ab)users :)
 263                 if not (reply and reply[#reply] and reply[#reply].a) then
 264                         local count = max_dns_depth;
 265                         reply = dns.peek(connect_host, "CNAME", "IN");
 266                         while count > 0 and reply and reply[#reply] and not reply[#reply].a and reply[#reply].cname do
 267                                 log("debug", "Looking up %s (DNS depth is %d)", tostring(reply[#reply].cname), count);
 268                                 reply = dns.peek(reply[#reply].cname, "A", "IN") or dns.peek(reply[#reply].cname, "CNAME", "IN");
 269                                 count = count - 1;
 270                         end
 271                 end
 272                 -- end of CNAME resolving
 273
 274                 if reply and reply[#reply] and reply[#reply].a then
 275                         log("debug", "DNS reply for %s gives us %s", connect_host, reply[#reply].a);
 276                         return make_connect(host_session, reply[#reply].a, connect_port);
 277                 else
 278                         log("debug", "DNS lookup failed to get a response for %s", connect_host);
 279                         if not attempt_connection(host_session, "name resolution failed") then -- Retry if we can
 280                                 log("debug", "No other records to try for %s - destroying", host_session.to_host);
 281                                 destroy_session(host_session); -- End of the line, we can't
 282                         end
 283                 end
 284         end, connect_host, "A", "IN");
 285
 286         -- Set handler for DNS timeout
 287         add_task(dns_timeout, function ()
 288                 if handle then
 289                         adns.cancel(handle, true);
 290                 end
 291         end);
 292
 293         return true;
 294 end
 295
 296 function make_connect(host_session, connect_host, connect_port)
 297         host_session.log("info", "Beginning new connection attempt to %s (%s:%d)", host_session.to_host, connect_host, connect_port);
 298         -- Ok, we're going to try to connect
 299
 300         local from_host, to_host = host_session.from_host, host_session.to_host;
 301
 302         local conn, handler = socket.tcp()
 303
 304         conn:settimeout(0);
 305         local success, err = conn:connect(connect_host, connect_port);
 306         if not success and err ~= "timeout" then
 307                 log("warn", "s2s connect() to %s (%s:%d) failed: %s", host_session.to_host, connect_host, connect_port, err);
 308                 return false, err;
 309         end
 310
 311         local cl = connlisteners_get("xmppserver");
 312         conn = wrapclient(conn, connect_host, connect_port, cl, cl.default_mode or 1, hosts[from_host].ssl_ctx, false );
 313         host_session.conn = conn;
 314
 315         -- Register this outgoing connection so that xmppserver_listener knows about it
 316         -- otherwise it will assume it is a new incoming connection
 317         cl.register_outgoing(conn, host_session);
 318
 319         local w, log = conn.write, host_session.log;
 320         host_session.sends2s = function (t) log("debug", "sending: %s", (t.top_tag and t:top_tag()) or t:match("^[^>]*>?")); w(tostring(t)); end
 321
 322         conn.write(format([[<stream:stream xmlns='jabber:server' xmlns:db='jabber:server:dialback' xmlns:stream='http://etherx.jabber.org/streams' from='%s' to='%s' version='1.0' xml:lang='en'>]], from_host, to_host));
 323         log("debug", "Connection attempt in progress...");
 324         add_task(connect_timeout, function ()
 325                 if host_session.conn ~= conn or
 326                    host_session.type == "s2sout" or
 327                    host_session.connecting then
 328                         return; -- Ok, we're connect[ed|ing]
 329                 end
 330                 -- Not connected, need to close session and clean up
 331                 (host_session.log or log)("warn", "Destroying incomplete session %s->%s due to inactivity",
 332                     host_session.from_host or "(unknown)", host_session.to_host or "(unknown)");
 333                 host_session:close("connection-timeout");
 334         end);
 335         return true;
 336 end
 337
 338 function streamopened(session, attr)
 339         local send = session.sends2s;
 340
 341         -- TODO: #29: SASL/TLS on s2s streams
 342         session.version = tonumber(attr.version) or 0;
 343
 344         if session.secure == false then
 345                 session.secure = true;
 346         end
 347
 348         if session.version >= 1.0 and not (attr.to and attr.from) then
 349
 350                 (session.log or log)("warn", "Remote of stream "..(session.from_host or "(unknown)").."->"..(session.to_host or "(unknown)")
 351                         .." failed to specify to (%s) and/or from (%s) hostname as per RFC", tostring(attr.to), tostring(attr.from));
 352         end
 353
 354         if session.direction == "incoming" then
 355                 -- Send a reply stream header
 356                 session.to_host = attr.to and nameprep(attr.to);
 357                 session.from_host = attr.from and nameprep(attr.from);
 358
 359                 session.streamid = uuid_gen();
 360                 (session.log or log)("debug", "incoming s2s received <stream:stream>");
 361                 send("<?xml version='1.0'?>");
 362                 send(stanza("stream:stream", { xmlns='jabber:server', ["xmlns:db"]='jabber:server:dialback',
 363                                 ["xmlns:stream"]='http://etherx.jabber.org/streams', id=session.streamid, from=session.to_host, version=(session.version > 0 and "1.0" or nil) }):top_tag());
 364                 if session.to_host and not hosts[session.to_host] then
 365                         -- Attempting to connect to a host we don't serve
 366                         session:close({ condition = "host-unknown"; text = "This host does not serve "..session.to_host });
 367                         return;
 368                 end
 369                 if session.version >= 1.0 then
 370                         local features = st.stanza("stream:features");
 371
 372                         if session.to_host then
 373                                 hosts[session.to_host].events.fire_event("s2s-stream-features", { session = session, features = features });
 374                         else
 375                                 (session.log or log)("warn", "No 'to' on stream header from %s means we can't offer any features", session.from_host or "unknown host");
 376                         end
 377
 378                         log("debug", "Sending stream features: %s", tostring(features));
 379                         send(features);
 380                 end
 381         elseif session.direction == "outgoing" then
 382                 -- If we are just using the connection for verifying dialback keys, we won't try and auth it
 383                 if not attr.id then error("stream response did not give us a streamid!!!"); end
 384                 session.streamid = attr.id;
 385
 386                 -- Send unauthed buffer
 387                 -- (stanzas which are fine to send before dialback)
 388                 -- Note that this is *not* the stanza queue (which
 389                 -- we can only send if auth succeeds) :)
 390                 local send_buffer = session.send_buffer;
 391                 if send_buffer and #send_buffer > 0 then
 392                         log("debug", "Sending s2s send_buffer now...");
 393                         for i, data in ipairs(send_buffer) do
 394                                 session.sends2s(data);
 395                                 send_buffer[i] = nil;
 396                         end
 397                 end
 398                 session.send_buffer = nil;
 399
 400                 -- If server is pre-1.0, don't wait for features, just do dialback
 401                 if session.version < 1.0 then
 402                         if not session.dialback_verifying then
 403                                 log("debug", "Initiating dialback...");
 404                                 initiate_dialback(session);
 405                         else
 406                                 mark_connected(session);
 407                         end
 408                 end
 409         end
 410
 411         session.notopen = nil;
 412 end
 413
 414 function streamclosed(session)
 415         (session.log or log)("debug", "</stream:stream>");
 416         if session.sends2s then
 417                 session.sends2s("</stream:stream>");
 418         end
 419         session.notopen = true;
 420 end
 421
 422 function initiate_dialback(session)
 423         -- generate dialback key
 424         session.dialback_key = generate_dialback(session.streamid, session.to_host, session.from_host);
 425         session.sends2s(format("<db:result from='%s' to='%s'>%s</db:result>", session.from_host, session.to_host, session.dialback_key));
 426         session.log("info", "sent dialback key on outgoing s2s stream");
 427 end
 428
 429 function generate_dialback(id, to, from)
 430         return sha256_hash(id..to..from..dialback_secret, true);
 431 end
 432
 433 function verify_dialback(id, to, from, key)
 434         return key == generate_dialback(id, to, from);
 435 end
 436
 437 function make_authenticated(session, host)
 438         if session.type == "s2sout_unauthed" then
 439                 session.type = "s2sout";
 440         elseif session.type == "s2sin_unauthed" then
 441                 session.type = "s2sin";
 442                 if host then
 443                         session.hosts[host].authed = true;
 444                 end
 445         elseif session.type == "s2sin" and host then
 446                 session.hosts[host].authed = true;
 447         else
 448                 return false;
 449         end
 450         session.log("debug", "connection %s->%s is now authenticated", session.from_host or "(unknown)", session.to_host or "(unknown)");
 451
 452         mark_connected(session);
 453
 454         return true;
 455 end
 456
 457 -- Stream is authorised, and ready for normal stanzas
 458 function mark_connected(session)
 459         local sendq, send = session.sendq, session.sends2s;
 460
 461         local from, to = session.from_host, session.to_host;
 462
 463         session.log("info", session.direction.." s2s connection "..from.."->"..to.." complete");
 464
 465         local send_to_host = send_to_host;
 466         function session.send(data) send_to_host(to, from, data); end
 467
 468
 469         if session.direction == "outgoing" then
 470                 if sendq then
 471                         session.log("debug", "sending "..#sendq.." queued stanzas across new outgoing connection to "..session.to_host);
 472                         for i, data in ipairs(sendq) do
 473                                 send(data[1]);
 474                                 sendq[i] = nil;
 475                         end
 476                         session.sendq = nil;
 477                 end
 478
 479                 session.srv_hosts = nil;
 480         end
 481 end
 482
 483 function destroy_session(session)
 484         (session.log or log)("info", "Destroying "..tostring(session.direction).." session "..tostring(session.from_host).."->"..tostring(session.to_host));
 485
 486         if session.direction == "outgoing" then
 487                 hosts[session.from_host].s2sout[session.to_host] = nil;
 488                 bounce_sendq(session);
 489         elseif session.direction == "incoming" then
 490                 incoming_s2s[session] = nil;
 491         end
 492
 493         for k in pairs(session) do
 494                 if k ~= "trace" then
 495                         session[k] = nil;
 496                 end
 497         end
 498 end
 499
 500 return _M;