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