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