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 adns, dns = require "net.adns", require "net.dns";
  40 local config = require "core.configmanager";
  41 local connect_timeout = config.get("*", "core", "s2s_timeout") or 60;
  42 local dns_timeout = config.get("*", "core", "dns_timeout") or 60;
  43 local max_dns_depth = config.get("*", "core", "dns_max_depth") or 3;
  44
  45 incoming_s2s = {};
  46 _G.prosody.incoming_s2s = incoming_s2s;
  47 local incoming_s2s = incoming_s2s;
  48
  49 module "s2smanager"
  50
  51 local function compare_srv_priorities(a,b) return a.priority < b.priority or a.weight < b.weight; end
  52
  53 local function bounce_sendq(session, reason)
  54         local sendq = session.sendq;
  55         if sendq then
  56                 session.log("info", "sending error replies for "..#sendq.." queued stanzas because of failed outgoing connection to "..tostring(session.to_host));
  57                 local dummy = {
  58                         type = "s2sin";
  59                         send = function(s)
  60                                 (session.log or log)("error", "Replying to to an s2s error reply, please report this! Traceback: %s", get_traceback());
  61                         end;
  62                         dummy = true;
  63                 };
  64                 for i, data in ipairs(sendq) do
  65                         local reply = data[2];
  66                         local xmlns = reply.attr.xmlns;
  67                         if not xmlns or xmlns == "jabber:client" or xmlns == "jabber:server" then
  68                                 reply.attr.type = "error";
  69                                 reply:tag("error", {type = "cancel"})
  70                                         :tag("remote-server-not-found", {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"}):up();
  71                                 if reason then
  72                                         reply:tag("text", {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"}):text("Connection failed: "..reason):up();
  73                                 end
  74                                 core_process_stanza(dummy, reply);
  75                         end
  76                         sendq[i] = nil;
  77                 end
  78                 session.sendq = nil;
  79         end
  80 end
  81
  82 function send_to_host(from_host, to_host, data)
  83         if not hosts[from_host] then
  84                 log("warn", "Attempt to send stanza from %s - a host we don't serve", from_host);
  85                 return false;
  86         end
  87         local host = hosts[from_host].s2sout[to_host];
  88         if host then
  89                 -- We have a connection to this host already
  90                 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
  91                         (host.log or log)("debug", "trying to send over unauthed s2sout to "..to_host);
  92
  93                         -- Queue stanza until we are able to send it
  94                         if host.sendq then t_insert(host.sendq, {tostring(data), st.reply(data)});
  95                         else host.sendq = { {tostring(data), st.reply(data)} }; end
  96                         host.log("debug", "stanza [%s] queued ", data.name);
  97                 elseif host.type == "local" or host.type == "component" then
  98                         log("error", "Trying to send a stanza to ourselves??")
  99                         log("error", "Traceback: %s", get_traceback());
 100                         log("error", "Stanza: %s", tostring(data));
 101                 else
 102                         (host.log or log)("debug", "going to send stanza to "..to_host.." from "..from_host);
 103                         -- FIXME
 104                         if host.from_host ~= from_host then
 105                                 log("error", "WARNING! This might, possibly, be a bug, but it might not...");
 106                                 log("error", "We are going to send from %s instead of %s", tostring(host.from_host), tostring(from_host));
 107                         end
 108                         host.sends2s(data);
 109                         host.log("debug", "stanza sent over "..host.type);
 110                 end
 111         else
 112                 log("debug", "opening a new outgoing connection for this stanza");
 113                 local host_session = new_outgoing(from_host, to_host);
 114
 115                 -- Store in buffer
 116                 host_session.sendq = { {tostring(data), st.reply(data)} };
 117                 log("debug", "stanza [%s] queued until connection complete", tostring(data.name));
 118                 if (not host_session.connecting) and (not host_session.conn) then
 119                         log("warn", "Connection to %s failed already, destroying session...", to_host);
 120                         destroy_session(host_session);
 121                 end
 122         end
 123 end
 124
 125 local open_sessions = 0;
 126
 127 function new_incoming(conn)
 128         local session = { conn = conn, type = "s2sin_unauthed", direction = "incoming", hosts = {} };
 129         if true then
 130                 session.trace = newproxy(true);
 131                 getmetatable(session.trace).__gc = function () open_sessions = open_sessions - 1; end;
 132         end
 133         open_sessions = open_sessions + 1;
 134         local w, log = conn.write, logger_init("s2sin"..tostring(conn):match("[a-f0-9]+$"));
 135         session.log = log;
 136         session.sends2s = function (t) log("debug", "sending: %s", t.top_tag and t:top_tag() or t:match("^([^>]*>?)")); w(conn, tostring(t)); end
 137         incoming_s2s[session] = true;
 138         add_task(connect_timeout, function ()
 139                 if session.conn ~= conn or
 140                    session.type == "s2sin" then
 141                         return; -- Ok, we're connect[ed|ing]
 142                 end
 143                 -- Not connected, need to close session and clean up
 144                 (session.log or log)("warn", "Destroying incomplete session %s->%s due to inactivity",
 145                     session.from_host or "(unknown)", session.to_host or "(unknown)");
 146                 session:close("connection-timeout");
 147         end);
 148         return session;
 149 end
 150
 151 function new_outgoing(from_host, to_host, connect)
 152                 local host_session = { to_host = to_host, from_host = from_host, host = from_host,
 153                                        notopen = true, type = "s2sout_unauthed", direction = "outgoing",
 154                                        open_stream = session_open_stream };
 155
 156                 hosts[from_host].s2sout[to_host] = host_session;
 157
 158                 local log;
 159                 do
 160                         local conn_name = "s2sout"..tostring(host_session):match("[a-f0-9]*$");
 161                         log = logger_init(conn_name);
 162                         host_session.log = log;
 163                 end
 164
 165                 if connect ~= false then
 166                         -- Kick the connection attempting machine into life
 167                         attempt_connection(host_session);
 168                 end
 169
 170                 if not host_session.sends2s then
 171                         -- A sends2s which buffers data (until the stream is opened)
 172                         -- note that data in this buffer will be sent before the stream is authed
 173                         -- and will not be ack'd in any way, successful or otherwise
 174                         local buffer;
 175                         function host_session.sends2s(data)
 176                                 if not buffer then
 177                                         buffer = {};
 178                                         host_session.send_buffer = buffer;
 179                                 end
 180                                 log("debug", "Buffering data on unconnected s2sout to %s", to_host);
 181                                 buffer[#buffer+1] = data;
 182                                 log("debug", "Buffered item %d: %s", #buffer, tostring(data));
 183                         end
 184                 end
 185
 186                 return host_session;
 187 end
 188
 189
 190 function attempt_connection(host_session, err)
 191         local from_host, to_host = host_session.from_host, host_session.to_host;
 192         local connect_host, connect_port = idna_to_ascii(to_host), 5269;
 193
 194         if not connect_host then
 195                 return false;
 196         end
 197
 198         if not err then -- This is our first attempt
 199                 log("debug", "First attempt to connect to %s, starting with SRV lookup...", to_host);
 200                 host_session.connecting = true;
 201                 local handle;
 202                 handle = adns.lookup(function (answer)
 203                         handle = nil;
 204                         host_session.connecting = nil;
 205                         if answer then
 206                                 log("debug", to_host.." has SRV records, handling...");
 207                                 local srv_hosts = {};
 208                                 host_session.srv_hosts = srv_hosts;
 209                                 for _, record in ipairs(answer) do
 210                                         t_insert(srv_hosts, record.srv);
 211                                 end
 212                                 t_sort(srv_hosts, compare_srv_priorities);
 213
 214                                 local srv_choice = srv_hosts[1];
 215                                 host_session.srv_choice = 1;
 216                                 if srv_choice then
 217                                         connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
 218                                         log("debug", "Best record found, will connect to %s:%d", connect_host, connect_port);
 219                                 end
 220                         else
 221                                 log("debug", to_host.." has no SRV records, falling back to A");
 222                         end
 223                         -- Try with SRV, or just the plain hostname if no SRV
 224                         local ok, err = try_connect(host_session, connect_host, connect_port);
 225                         if not ok then
 226                                 if not attempt_connection(host_session, err) then
 227                                         -- No more attempts will be made
 228                                         destroy_session(host_session, err);
 229                                 end
 230                         end
 231                 end, "_xmpp-server._tcp."..connect_host..".", "SRV");
 232
 233                 -- Set handler for DNS timeout
 234                 add_task(dns_timeout, function ()
 235                         if handle then
 236                                 adns.cancel(handle, true);
 237                         end
 238                 end);
 239
 240                 log("debug", "DNS lookup for %s sent, waiting for response before we can connect", to_host);
 241                 return true; -- Attempt in progress
 242         elseif host_session.srv_hosts and #host_session.srv_hosts > host_session.srv_choice then -- Not our first attempt, and we also have SRV
 243                 host_session.srv_choice = host_session.srv_choice + 1;
 244                 local srv_choice = host_session.srv_hosts[host_session.srv_choice];
 245                 connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
 246                 host_session.log("info", "Connection failed (%s). Attempt #%d: This time to %s:%d", tostring(err), host_session.srv_choice, connect_host, connect_port);
 247         else
 248                 host_session.log("info", "Out of connection options, can't connect to %s", tostring(host_session.to_host));
 249                 -- We're out of options
 250                 return false;
 251         end
 252
 253         if not (connect_host and connect_port) then
 254                 -- Likely we couldn't resolve DNS
 255                 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));
 256                 return false;
 257         end
 258
 259         return try_connect(host_session, connect_host, connect_port);
 260 end
 261
 262 function try_connect(host_session, connect_host, connect_port)
 263         host_session.connecting = true;
 264         local handle;
 265         handle = adns.lookup(function (reply)
 266                 handle = nil;
 267                 host_session.connecting = nil;
 268
 269                 -- COMPAT: This is a compromise for all you CNAME-(ab)users :)
 270                 if not (reply and reply[#reply] and reply[#reply].a) then
 271                         local count = max_dns_depth;
 272                         reply = dns.peek(connect_host, "CNAME", "IN");
 273                         while count > 0 and reply and reply[#reply] and not reply[#reply].a and reply[#reply].cname do
 274                                 log("debug", "Looking up %s (DNS depth is %d)", tostring(reply[#reply].cname), count);
 275                                 reply = dns.peek(reply[#reply].cname, "A", "IN") or dns.peek(reply[#reply].cname, "CNAME", "IN");
 276                                 count = count - 1;
 277                         end
 278                 end
 279                 -- end of CNAME resolving
 280
 281                 if reply and reply[#reply] and reply[#reply].a then
 282                         log("debug", "DNS reply for %s gives us %s", connect_host, reply[#reply].a);
 283                         return make_connect(host_session, reply[#reply].a, connect_port);
 284                 else
 285                         log("debug", "DNS lookup failed to get a response for %s", connect_host);
 286                         if not attempt_connection(host_session, "name resolution failed") then -- Retry if we can
 287                                 log("debug", "No other records to try for %s - destroying", host_session.to_host);
 288                                 destroy_session(host_session, "DNS resolution failed"); -- End of the line, we can't
 289                         end
 290                 end
 291         end, connect_host, "A", "IN");
 292
 293         -- Set handler for DNS timeout
 294         add_task(dns_timeout, function ()
 295                 if handle then
 296                         adns.cancel(handle, true);
 297                 end
 298         end);
 299
 300         return true;
 301 end
 302
 303 function make_connect(host_session, connect_host, connect_port)
 304         host_session.log("info", "Beginning new connection attempt to %s (%s:%d)", host_session.to_host, connect_host, connect_port);
 305         -- Ok, we're going to try to connect
 306
 307         local from_host, to_host = host_session.from_host, host_session.to_host;
 308
 309         local conn, handler = socket.tcp()
 310
 311         if not conn then
 312                 log("warn", "Failed to create outgoing connection, system error: %s", handler);
 313                 return false, handler;
 314         end
 315
 316         conn:settimeout(0);
 317         local success, err = conn:connect(connect_host, connect_port);
 318         if not success and err ~= "timeout" then
 319                 log("warn", "s2s connect() to %s (%s:%d) failed: %s", host_session.to_host, connect_host, connect_port, err);
 320                 return false, err;
 321         end
 322
 323         local cl = connlisteners_get("xmppserver");
 324         conn = wrapclient(conn, connect_host, connect_port, cl, cl.default_mode or 1 );
 325         host_session.conn = conn;
 326
 327         -- Register this outgoing connection so that xmppserver_listener knows about it
 328         -- otherwise it will assume it is a new incoming connection
 329         cl.register_outgoing(conn, host_session);
 330
 331         local w, log = conn.write, host_session.log;
 332         host_session.sends2s = function (t) log("debug", "sending: %s", (t.top_tag and t:top_tag()) or t:match("^[^>]*>?")); w(conn, tostring(t)); end
 333
 334         host_session:open_stream(from_host, to_host);
 335
 336         log("debug", "Connection attempt in progress...");
 337         add_task(connect_timeout, function ()
 338                 if host_session.conn ~= conn or
 339                    host_session.type == "s2sout" or
 340                    host_session.connecting then
 341                         return; -- Ok, we're connect[ed|ing]
 342                 end
 343                 -- Not connected, need to close session and clean up
 344                 (host_session.log or log)("warn", "Destroying incomplete session %s->%s due to inactivity",
 345                     host_session.from_host or "(unknown)", host_session.to_host or "(unknown)");
 346                 host_session:close("connection-timeout");
 347         end);
 348         return true;
 349 end
 350
 351 function session_open_stream(session, from, to)
 352         session.sends2s(st.stanza("stream:stream", {
 353                 xmlns='jabber:server', ["xmlns:db"]='jabber:server:dialback',
 354                 ["xmlns:stream"]='http://etherx.jabber.org/streams',
 355                 from=from, to=to, version='1.0', ["xml:lang"]='en'}):top_tag());
 356 end
 357
 358 function streamopened(session, attr)
 359         local send = session.sends2s;
 360
 361         -- TODO: #29: SASL/TLS on s2s streams
 362         session.version = tonumber(attr.version) or 0;
 363
 364         if session.secure == false then
 365                 session.secure = true;
 366         end
 367
 368         if session.version >= 1.0 and not (attr.to and attr.from) then
 369                 (session.log or log)("warn", "Remote of stream "..(session.from_host or "(unknown)").."->"..(session.to_host or "(unknown)")
 370                         .." failed to specify to (%s) and/or from (%s) hostname as per RFC", tostring(attr.to), tostring(attr.from));
 371         end
 372
 373         if session.direction == "incoming" then
 374                 -- Send a reply stream header
 375                 session.to_host = attr.to and nameprep(attr.to);
 376                 session.from_host = attr.from and nameprep(attr.from);
 377
 378                 session.streamid = uuid_gen();
 379                 (session.log or log)("debug", "incoming s2s received <stream:stream>");
 380                 if session.to_host and not hosts[session.to_host] then
 381                         -- Attempting to connect to a host we don't serve
 382                         session:close({ condition = "host-unknown"; text = "This host does not serve "..session.to_host });
 383                         return;
 384                 end
 385                 send("<?xml version='1.0'?>");
 386                 send(stanza("stream:stream", { xmlns='jabber:server', ["xmlns:db"]='jabber:server:dialback',
 387                                 ["xmlns:stream"]='http://etherx.jabber.org/streams', id=session.streamid, from=session.to_host, to=session.from_host, version=(session.version > 0 and "1.0" or nil) }):top_tag());
 388                 if session.version >= 1.0 then
 389                         local features = st.stanza("stream:features");
 390
 391                         if session.to_host then
 392                                 hosts[session.to_host].events.fire_event("s2s-stream-features", { session = session, features = features });
 393                         else
 394                                 (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");
 395                         end
 396
 397                         log("debug", "Sending stream features: %s", tostring(features));
 398                         send(features);
 399                 end
 400         elseif session.direction == "outgoing" then
 401                 -- If we are just using the connection for verifying dialback keys, we won't try and auth it
 402                 if not attr.id then error("stream response did not give us a streamid!!!"); end
 403                 session.streamid = attr.id;
 404
 405                 -- Send unauthed buffer
 406                 -- (stanzas which are fine to send before dialback)
 407                 -- Note that this is *not* the stanza queue (which
 408                 -- we can only send if auth succeeds) :)
 409                 local send_buffer = session.send_buffer;
 410                 if send_buffer and #send_buffer > 0 then
 411                         log("debug", "Sending s2s send_buffer now...");
 412                         for i, data in ipairs(send_buffer) do
 413                                 session.sends2s(tostring(data));
 414                                 send_buffer[i] = nil;
 415                         end
 416                 end
 417                 session.send_buffer = nil;
 418
 419                 -- If server is pre-1.0, don't wait for features, just do dialback
 420                 if session.version < 1.0 then
 421                         if not session.dialback_verifying then
 422                                 log("debug", "Initiating dialback...");
 423                                 initiate_dialback(session);
 424                         else
 425                                 mark_connected(session);
 426                         end
 427                 end
 428         end
 429         session.notopen = nil;
 430 end
 431
 432 function streamclosed(session)
 433         (session.log or log)("debug", "</stream:stream>");
 434         if session.sends2s then
 435                 session.sends2s("</stream:stream>");
 436         end
 437         session.notopen = true;
 438 end
 439
 440 function initiate_dialback(session)
 441         -- generate dialback key
 442         session.dialback_key = generate_dialback(session.streamid, session.to_host, session.from_host);
 443         session.sends2s(format("<db:result from='%s' to='%s'>%s</db:result>", session.from_host, session.to_host, session.dialback_key));
 444         session.log("info", "sent dialback key on outgoing s2s stream");
 445 end
 446
 447 function generate_dialback(id, to, from)
 448         return sha256_hash(id..to..from..hosts[from].dialback_secret, true);
 449 end
 450
 451 function verify_dialback(id, to, from, key)
 452         return key == generate_dialback(id, to, from);
 453 end
 454
 455 function make_authenticated(session, host)
 456         if not session.secure then
 457                 local local_host = session.direction == "incoming" and session.to_host or session.from_host;
 458                 if config.get(local_host, "core", "s2s_require_encryption") then
 459                         session:close({
 460                                 condition = "policy-violation",
 461                                 text = "Encrypted server-to-server communication is required but was not "
 462                                        ..((session.direction == "outgoing" and "offered") or "used")
 463                         });
 464                 end
 465         end
 466         if session.type == "s2sout_unauthed" then
 467                 session.type = "s2sout";
 468         elseif session.type == "s2sin_unauthed" then
 469                 session.type = "s2sin";
 470                 if host then
 471                         session.hosts[host].authed = true;
 472                 end
 473         elseif session.type == "s2sin" and host then
 474                 session.hosts[host].authed = true;
 475         else
 476                 return false;
 477         end
 478         session.log("debug", "connection %s->%s is now authenticated", session.from_host or "(unknown)", session.to_host or "(unknown)");
 479
 480         mark_connected(session);
 481
 482         return true;
 483 end
 484
 485 -- Stream is authorised, and ready for normal stanzas
 486 function mark_connected(session)
 487         local sendq, send = session.sendq, session.sends2s;
 488
 489         local from, to = session.from_host, session.to_host;
 490
 491         session.log("info", session.direction.." s2s connection "..from.."->"..to.." complete");
 492
 493         local send_to_host = send_to_host;
 494         function session.send(data) send_to_host(to, from, data); end
 495
 496
 497         if session.direction == "outgoing" then
 498                 if sendq then
 499                         session.log("debug", "sending "..#sendq.." queued stanzas across new outgoing connection to "..session.to_host);
 500                         for i, data in ipairs(sendq) do
 501                                 send(data[1]);
 502                                 sendq[i] = nil;
 503                         end
 504                         session.sendq = nil;
 505                 end
 506
 507                 session.srv_hosts = nil;
 508         end
 509 end
 510
 511 function destroy_session(session, reason)
 512         (session.log or log)("info", "Destroying "..tostring(session.direction).." session "..tostring(session.from_host).."->"..tostring(session.to_host));
 513
 514         if session.direction == "outgoing" then
 515                 hosts[session.from_host].s2sout[session.to_host] = nil;
 516                 bounce_sendq(session, reason);
 517         elseif session.direction == "incoming" then
 518                 incoming_s2s[session] = nil;
 519         end
 520
 521         for k in pairs(session) do
 522                 if k ~= "trace" then
 523                         session[k] = nil;
 524                 end
 525         end
 526 end
 527
 528 return _M;