core/s2smanager.lua

   1 -- Prosody IM
   2 -- Copyright (C) 2008-2010 Matthew Wild
   3 -- Copyright (C) 2008-2010 Waqas Hussain
   4 --
   5 -- This project is MIT/X11 licensed. Please see the
   6 -- COPYING file in the source package for more information.
   7 --
   8
   9
  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, type, error, tonumber, setmetatable
  20     = tostring, pairs, ipairs, getmetatable, newproxy, type, error, tonumber, setmetatable;
  21
  22 local idna_to_ascii = require "util.encodings".idna.to_ascii;
  23 local connlisteners_get = require "net.connlisteners".get;
  24 local initialize_filters = require "util.filters".initialize;
  25 local wrapclient = require "net.server".wrapclient;
  26 local st = require "stanza";
  27 local stanza = st.stanza;
  28 local nameprep = require "util.encodings".stringprep.nameprep;
  29 local cert_verify_identity = require "util.x509".verify_identity;
  30 local new_ip = require "util.ip".new_ip;
  31 local rfc3484_dest = require "util.rfc3484".destination;
  32
  33 local fire_event = prosody.events.fire_event;
  34 local uuid_gen = require "util.uuid".generate;
  35
  36 local logger_init = require "util.logger".init;
  37
  38 local log = logger_init("s2smanager");
  39
  40 local sha256_hash = require "util.hashes".sha256;
  41
  42 local adns, dns = require "net.adns", require "net.dns";
  43 local config = require "core.configmanager";
  44 local connect_timeout = config.get("*", "core", "s2s_timeout") or 60;
  45 local dns_timeout = config.get("*", "core", "dns_timeout") or 15;
  46 local max_dns_depth = config.get("*", "core", "dns_max_depth") or 3;
  47 local sources;
  48
  49 dns.settimeout(dns_timeout);
  50
  51 local prosody = _G.prosody;
  52 incoming_s2s = {};
  53 prosody.incoming_s2s = incoming_s2s;
  54 local incoming_s2s = incoming_s2s;
  55
  56 module "s2smanager"
  57
  58 function compare_srv_priorities(a,b)
  59         return a.priority < b.priority or (a.priority == b.priority and a.weight > b.weight);
  60 end
  61
  62 local bouncy_stanzas = { message = true, presence = true, iq = true };
  63 local function bounce_sendq(session, reason)
  64         local sendq = session.sendq;
  65         if sendq then
  66                 session.log("info", "sending error replies for "..#sendq.." queued stanzas because of failed outgoing connection to "..tostring(session.to_host));
  67                 local dummy = {
  68                         type = "s2sin";
  69                         send = function(s)
  70                                 (session.log or log)("error", "Replying to to an s2s error reply, please report this! Traceback: %s", get_traceback());
  71                         end;
  72                         dummy = true;
  73                 };
  74                 for i, data in ipairs(sendq) do
  75                         local reply = data[2];
  76                         if reply and not(reply.attr.xmlns) and bouncy_stanzas[reply.name] then
  77                                 reply.attr.type = "error";
  78                                 reply:tag("error", {type = "cancel"})
  79                                         :tag("remote-server-not-found", {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"}):up();
  80                                 if reason then
  81                                         reply:tag("text", {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"})
  82                                                 :text("Server-to-server connection failed: "..reason):up();
  83                                 end
  84                                 core_process_stanza(dummy, reply);
  85                         end
  86                         sendq[i] = nil;
  87                 end
  88                 session.sendq = nil;
  89         end
  90 end
  91
  92 function send_to_host(from_host, to_host, data)
  93         if not hosts[from_host] then
  94                 log("warn", "Attempt to send stanza from %s - a host we don't serve", from_host);
  95                 return false;
  96         end
  97         local host = hosts[from_host].s2sout[to_host];
  98         if host then
  99                 -- We have a connection to this host already
 100                 if host.type == "s2sout_unauthed" and (data.name ~= "db:verify" or not host.dialback_key) then
 101                         (host.log or log)("debug", "trying to send over unauthed s2sout to "..to_host);
 102
 103                         -- Queue stanza until we are able to send it
 104                         if host.sendq then t_insert(host.sendq, {tostring(data), data.attr.type ~= "error" and data.attr.type ~= "result" and st.reply(data)});
 105                         else host.sendq = { {tostring(data), data.attr.type ~= "error" and data.attr.type ~= "result" and st.reply(data)} }; end
 106                         host.log("debug", "stanza [%s] queued ", data.name);
 107                 elseif host.type == "local" or host.type == "component" then
 108                         log("error", "Trying to send a stanza to ourselves??")
 109                         log("error", "Traceback: %s", get_traceback());
 110                         log("error", "Stanza: %s", tostring(data));
 111                         return false;
 112                 else
 113                         (host.log or log)("debug", "going to send stanza to "..to_host.." from "..from_host);
 114                         -- FIXME
 115                         if host.from_host ~= from_host then
 116                                 log("error", "WARNING! This might, possibly, be a bug, but it might not...");
 117                                 log("error", "We are going to send from %s instead of %s", tostring(host.from_host), tostring(from_host));
 118                         end
 119                         host.sends2s(data);
 120                         host.log("debug", "stanza sent over "..host.type);
 121                 end
 122         else
 123                 log("debug", "opening a new outgoing connection for this stanza");
 124                 local host_session = new_outgoing(from_host, to_host);
 125
 126                 -- Store in buffer
 127                 host_session.sendq = { {tostring(data), data.attr.type ~= "error" and data.attr.type ~= "result" and st.reply(data)} };
 128                 log("debug", "stanza [%s] queued until connection complete", tostring(data.name));
 129                 if (not host_session.connecting) and (not host_session.conn) then
 130                         log("warn", "Connection to %s failed already, destroying session...", to_host);
 131                         if not destroy_session(host_session, "Connection failed") then
 132                                 -- Already destroyed, we need to bounce our stanza
 133                                 bounce_sendq(host_session, host_session.destruction_reason);
 134                         end
 135                         return false;
 136                 end
 137         end
 138         return true;
 139 end
 140
 141 local open_sessions = 0;
 142
 143 function new_incoming(conn)
 144         local session = { conn = conn, type = "s2sin_unauthed", direction = "incoming", hosts = {} };
 145         if true then
 146                 session.trace = newproxy(true);
 147                 getmetatable(session.trace).__gc = function () open_sessions = open_sessions - 1; end;
 148         end
 149         open_sessions = open_sessions + 1;
 150         local w, log = conn.write, logger_init("s2sin"..tostring(conn):match("[a-f0-9]+$"));
 151         session.log = log;
 152         local filter = initialize_filters(session);
 153         session.sends2s = function (t)
 154                 log("debug", "sending: %s", t.top_tag and t:top_tag() or t:match("^([^>]*>?)"));
 155                 if t.name then
 156                         t = filter("stanzas/out", t);
 157                 end
 158                 if t then
 159                         t = filter("bytes/out", tostring(t));
 160                         if t then
 161                                 return w(conn, t);
 162                         end
 163                 end
 164         end
 165         incoming_s2s[session] = true;
 166         add_task(connect_timeout, function ()
 167                 if session.conn ~= conn or
 168                    session.type == "s2sin" then
 169                         return; -- Ok, we're connect[ed|ing]
 170                 end
 171                 -- Not connected, need to close session and clean up
 172                 (session.log or log)("debug", "Destroying incomplete session %s->%s due to inactivity",
 173                     session.from_host or "(unknown)", session.to_host or "(unknown)");
 174                 session:close("connection-timeout");
 175         end);
 176         return session;
 177 end
 178
 179 function new_outgoing(from_host, to_host, connect)
 180                 local host_session = { to_host = to_host, from_host = from_host, host = from_host,
 181                                        notopen = true, type = "s2sout_unauthed", direction = "outgoing",
 182                                        open_stream = session_open_stream };
 183
 184                 hosts[from_host].s2sout[to_host] = host_session;
 185
 186                 host_session.close = destroy_session; -- This gets replaced by xmppserver_listener later
 187
 188                 local log;
 189                 do
 190                         local conn_name = "s2sout"..tostring(host_session):match("[a-f0-9]*$");
 191                         log = logger_init(conn_name);
 192                         host_session.log = log;
 193                 end
 194
 195                 initialize_filters(host_session);
 196
 197                 if connect ~= false then
 198                         -- Kick the connection attempting machine into life
 199                         if not attempt_connection(host_session) then
 200                                 -- Intentionally not returning here, the
 201                                 -- session is needed, connected or not
 202                                 destroy_session(host_session);
 203                         end
 204                 end
 205
 206                 if not host_session.sends2s then
 207                         -- A sends2s which buffers data (until the stream is opened)
 208                         -- note that data in this buffer will be sent before the stream is authed
 209                         -- and will not be ack'd in any way, successful or otherwise
 210                         local buffer;
 211                         function host_session.sends2s(data)
 212                                 if not buffer then
 213                                         buffer = {};
 214                                         host_session.send_buffer = buffer;
 215                                 end
 216                                 log("debug", "Buffering data on unconnected s2sout to %s", to_host);
 217                                 buffer[#buffer+1] = data;
 218                                 log("debug", "Buffered item %d: %s", #buffer, tostring(data));
 219                         end
 220                 end
 221
 222                 return host_session;
 223 end
 224
 225
 226 function attempt_connection(host_session, err)
 227         local from_host, to_host = host_session.from_host, host_session.to_host;
 228         local connect_host, connect_port = to_host and idna_to_ascii(to_host), 5269;
 229
 230         if not connect_host then
 231                 return false;
 232         end
 233
 234         if not err then -- This is our first attempt
 235                 log("debug", "First attempt to connect to %s, starting with SRV lookup...", to_host);
 236                 host_session.connecting = true;
 237                 local handle;
 238                 handle = adns.lookup(function (answer)
 239                         handle = nil;
 240                         host_session.connecting = nil;
 241                         if answer then
 242                                 log("debug", to_host.." has SRV records, handling...");
 243                                 local srv_hosts = {};
 244                                 host_session.srv_hosts = srv_hosts;
 245                                 for _, record in ipairs(answer) do
 246                                         t_insert(srv_hosts, record.srv);
 247                                 end
 248                                 if #srv_hosts == 1 and srv_hosts[1].target == "." then
 249                                         log("debug", to_host.." does not provide a XMPP service");
 250                                         destroy_session(host_session, err); -- Nothing to see here
 251                                         return;
 252                                 end
 253                                 t_sort(srv_hosts, compare_srv_priorities);
 254
 255                                 local srv_choice = srv_hosts[1];
 256                                 host_session.srv_choice = 1;
 257                                 if srv_choice then
 258                                         connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
 259                                         log("debug", "Best record found, will connect to %s:%d", connect_host, connect_port);
 260                                 end
 261                         else
 262                                 log("debug", to_host.." has no SRV records, falling back to A");
 263                         end
 264                         -- Try with SRV, or just the plain hostname if no SRV
 265                         local ok, err = try_connect(host_session, connect_host, connect_port);
 266                         if not ok then
 267                                 if not attempt_connection(host_session, err) then
 268                                         -- No more attempts will be made
 269                                         destroy_session(host_session, err);
 270                                 end
 271                         end
 272                 end, "_xmpp-server._tcp."..connect_host..".", "SRV");
 273
 274                 return true; -- Attempt in progress
 275         elseif host_session.ip_hosts then
 276                 return try_connect(host_session, connect_host, connect_port, err);
 277         elseif host_session.srv_hosts and #host_session.srv_hosts > host_session.srv_choice then -- Not our first attempt, and we also have SRV
 278                 host_session.srv_choice = host_session.srv_choice + 1;
 279                 local srv_choice = host_session.srv_hosts[host_session.srv_choice];
 280                 connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
 281                 host_session.log("info", "Connection failed (%s). Attempt #%d: This time to %s:%d", tostring(err), host_session.srv_choice, connect_host, connect_port);
 282         else
 283                 host_session.log("info", "Out of connection options, can't connect to %s", tostring(host_session.to_host));
 284                 -- We're out of options
 285                 return false;
 286         end
 287
 288         if not (connect_host and connect_port) then
 289                 -- Likely we couldn't resolve DNS
 290                 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));
 291                 return false;
 292         end
 293
 294         return try_connect(host_session, connect_host, connect_port);
 295 end
 296
 297 function try_next_ip(host_session)
 298         host_session.connecting = nil;
 299         host_session.ip_choice = host_session.ip_choice + 1;
 300         local ip = host_session.ip_hosts[host_session.ip_choice];
 301         local ok, err= make_connect(host_session, ip.ip, ip.port);
 302         if not ok then
 303                 if not attempt_connection(host_session, err or "closed") then
 304                         err = err and (": "..err) or "";
 305                         destroy_session(host_session, "Connection failed"..err);
 306                 end
 307         end
 308 end
 309
 310 function try_connect(host_session, connect_host, connect_port, err)
 311         host_session.connecting = true;
 312
 313         if not err then
 314                 local IPs = {};
 315                 host_session.ip_hosts = IPs;
 316                 local handle4, handle6;
 317                 local has_other = false;
 318
 319                 if not sources then
 320                         sources =  {};
 321                         local cfg_sources = config.get("*", "core", "interface") or connlisteners_get("xmppserver").default_interface;
 322                         if type(cfg_sources) == "string" then
 323                                 cfg_sources = { cfg_sources };
 324                         end
 325                         for i, source in ipairs(cfg_sources) do
 326                                 if source == "*" then
 327                                         sources[i] = new_ip("0.0.0.0", "IPv4");
 328                                 else
 329                                         sources[i] = new_ip(source, (source:find(":") and "IPv6") or "IPv4");
 330                                 end
 331                         end
 332                 end
 333
 334                 handle4 = adns.lookup(function (reply, err)
 335                         handle4 = nil;
 336
 337                         -- COMPAT: This is a compromise for all you CNAME-(ab)users :)
 338                         if not (reply and reply[#reply] and reply[#reply].a) then
 339                                 local count = max_dns_depth;
 340                                 reply = dns.peek(connect_host, "CNAME", "IN");
 341                                 while count > 0 and reply and reply[#reply] and not reply[#reply].a and reply[#reply].cname do
 342                                         log("debug", "Looking up %s (DNS depth is %d)", tostring(reply[#reply].cname), count);
 343                                         reply = dns.peek(reply[#reply].cname, "A", "IN") or dns.peek(reply[#reply].cname, "CNAME", "IN");
 344                                         count = count - 1;
 345                                 end
 346                         end
 347                         -- end of CNAME resolving
 348
 349                         if reply and reply[#reply] and reply[#reply].a then
 350                                 for _, ip in ipairs(reply) do
 351                                         log("debug", "DNS reply for %s gives us %s", connect_host, ip.a);
 352                                         IPs[#IPs+1] = new_ip(ip.a, "IPv4");
 353                                 end
 354                         end
 355
 356                         if has_other then
 357                                 if #IPs > 0 then
 358                                         rfc3484_dest(host_session.ip_hosts, sources);
 359                                         for i = 1, #IPs do
 360                                                 IPs[i] = {ip = IPs[i], port = connect_port};
 361                                         end
 362                                         host_session.ip_choice = 0;
 363                                         try_next_ip(host_session);
 364                                 else
 365                                         log("debug", "DNS lookup failed to get a response for %s", connect_host);
 366                                         host_session.ip_hosts = nil;
 367                                         if not attempt_connection(host_session, "name resolution failed") then -- Retry if we can
 368                                                 log("debug", "No other records to try for %s - destroying", host_session.to_host);
 369                                                 err = err and (": "..err) or "";
 370                                                 destroy_session(host_session, "DNS resolution failed"..err); -- End of the line, we can't
 371                                         end
 372                                 end
 373                         else
 374                                 has_other = true;
 375                         end
 376                 end, connect_host, "A", "IN");
 377
 378                 handle6 = adns.lookup(function (reply, err)
 379                         handle6 = nil;
 380
 381                         if reply and reply[#reply] and reply[#reply].aaaa then
 382                                 for _, ip in ipairs(reply) do
 383                                         log("debug", "DNS reply for %s gives us %s", connect_host, ip.aaaa);
 384                                         IPs[#IPs+1] = new_ip(ip.aaaa, "IPv6");
 385                                 end
 386                         end
 387
 388                         if has_other then
 389                                 if #IPs > 0 then
 390                                         rfc3484_dest(host_session.ip_hosts, sources);
 391                                         for i = 1, #IPs do
 392                                                 IPs[i] = {ip = IPs[i], port = connect_port};
 393                                         end
 394                                         host_session.ip_choice = 0;
 395                                         try_next_ip(host_session);
 396                                 else
 397                                         log("debug", "DNS lookup failed to get a response for %s", connect_host);
 398                                         host_session.ip_hosts = nil;
 399                                         if not attempt_connection(host_session, "name resolution failed") then -- Retry if we can
 400                                                 log("debug", "No other records to try for %s - destroying", host_session.to_host);
 401                                                 err = err and (": "..err) or "";
 402                                                 destroy_session(host_session, "DNS resolution failed"..err); -- End of the line, we can't
 403                                         end
 404                                 end
 405                         else
 406                                 has_other = true;
 407                         end
 408                 end, connect_host, "AAAA", "IN");
 409
 410                 return true;
 411         elseif host_session.ip_hosts and #host_session.ip_hosts > host_session.ip_choice then -- Not our first attempt, and we also have IPs left to try
 412                 try_next_ip(host_session);
 413         else
 414                 host_session.ip_hosts = nil;
 415                 if not attempt_connection(host_session, "out of IP addresses") then -- Retry if we can
 416                         log("debug", "No other records to try for %s - destroying", host_session.to_host);
 417                         err = err and (": "..err) or "";
 418                         destroy_session(host_session, "Connecting failed"..err); -- End of the line, we can't
 419                         return false;
 420                 end
 421         end
 422
 423         return true;
 424 end
 425
 426 function make_connect(host_session, connect_host, connect_port)
 427         (host_session.log or log)("info", "Beginning new connection attempt to %s ([%s]:%d)", host_session.to_host, connect_host.addr, connect_port);
 428         -- Ok, we're going to try to connect
 429
 430         local from_host, to_host = host_session.from_host, host_session.to_host;
 431
 432         local conn, handler;
 433         if connect_host.proto == "IPv4" then
 434                 conn, handler = socket.tcp();
 435         elseif socket.tcp6 then
 436                 conn, handler = socket.tcp6();
 437         end
 438
 439         if not conn then
 440                 log("warn", "Failed to create outgoing connection, system error: %s", handler);
 441                 return false, handler;
 442         end
 443
 444         conn:settimeout(0);
 445         local success, err = conn:connect(connect_host.addr, connect_port);
 446         if not success and err ~= "timeout" then
 447                 log("warn", "s2s connect() to %s (%s:%d) failed: %s", host_session.to_host, connect_host.addr, connect_port, err);
 448                 return false, err;
 449         end
 450
 451         local cl = connlisteners_get("xmppserver");
 452         conn = wrapclient(conn, connect_host.addr, connect_port, cl, cl.default_mode or 1 );
 453         host_session.conn = conn;
 454
 455         local filter = initialize_filters(host_session);
 456         local w, log = conn.write, host_session.log;
 457         host_session.sends2s = function (t)
 458                 log("debug", "sending: %s", (t.top_tag and t:top_tag()) or t:match("^[^>]*>?"));
 459                 if t.name then
 460                         t = filter("stanzas/out", t);
 461                 end
 462                 if t then
 463                         t = filter("bytes/out", tostring(t));
 464                         if t then
 465                                 return w(conn, tostring(t));
 466                         end
 467                 end
 468         end
 469
 470         -- Register this outgoing connection so that xmppserver_listener knows about it
 471         -- otherwise it will assume it is a new incoming connection
 472         cl.register_outgoing(conn, host_session);
 473
 474         host_session:open_stream(from_host, to_host);
 475
 476         log("debug", "Connection attempt in progress...");
 477         add_task(connect_timeout, function ()
 478                 if host_session.conn ~= conn or
 479                    host_session.type == "s2sout" or
 480                    host_session.connecting then
 481                         return; -- Ok, we're connect[ed|ing]
 482                 end
 483                 -- Not connected, need to close session and clean up
 484                 (host_session.log or log)("warn", "Destroying incomplete session %s->%s due to inactivity",
 485                     host_session.from_host or "(unknown)", host_session.to_host or "(unknown)");
 486                 host_session:close("connection-timeout");
 487         end);
 488         return true;
 489 end
 490
 491 function session_open_stream(session, from, to)
 492         session.sends2s(st.stanza("stream:stream", {
 493                 xmlns='jabber:server', ["xmlns:db"]='jabber:server:dialback',
 494                 ["xmlns:stream"]='http://etherx.jabber.org/streams',
 495                 from=from, to=to, version='1.0', ["xml:lang"]='en'}):top_tag());
 496 end
 497
 498 local function check_cert_status(session)
 499         local conn = session.conn:socket()
 500         local cert
 501         if conn.getpeercertificate then
 502                 cert = conn:getpeercertificate()
 503         end
 504
 505         if cert then
 506                 local chain_valid, errors = conn:getpeerverification()
 507                 -- Is there any interest in printing out all/the number of errors here?
 508                 if not chain_valid then
 509                         (session.log or log)("debug", "certificate chain validation result: invalid");
 510                         session.cert_chain_status = "invalid";
 511                 else
 512                         (session.log or log)("debug", "certificate chain validation result: valid");
 513                         session.cert_chain_status = "valid";
 514
 515                         local host;
 516                         if session.direction == "incoming" then
 517                                 host = session.from_host;
 518                         else
 519                                 host = session.to_host;
 520                         end
 521
 522                         -- We'll go ahead and verify the asserted identity if the
 523                         -- connecting server specified one.
 524                         if host then
 525                                 if cert_verify_identity(host, "xmpp-server", cert) then
 526                                         session.cert_identity_status = "valid"
 527                                 else
 528                                         session.cert_identity_status = "invalid"
 529                                 end
 530                         end
 531                 end
 532         end
 533 end
 534
 535 function streamopened(session, attr)
 536         local send = session.sends2s;
 537
 538         -- TODO: #29: SASL/TLS on s2s streams
 539         session.version = tonumber(attr.version) or 0;
 540
 541         -- TODO: Rename session.secure to session.encrypted
 542         if session.secure == false then
 543                 session.secure = true;
 544         end
 545
 546         if session.direction == "incoming" then
 547                 -- Send a reply stream header
 548                 session.to_host = attr.to and nameprep(attr.to);
 549                 session.from_host = attr.from and nameprep(attr.from);
 550
 551                 session.streamid = uuid_gen();
 552                 (session.log or log)("debug", "Incoming s2s received %s", st.stanza("stream:stream", attr):top_tag());
 553                 if session.to_host then
 554                         if not hosts[session.to_host] then
 555                                 -- Attempting to connect to a host we don't serve
 556                                 session:close({
 557                                         condition = "host-unknown";
 558                                         text = "This host does not serve "..session.to_host
 559                                 });
 560                                 return;
 561                         elseif hosts[session.to_host].disallow_s2s then
 562                                 -- Attempting to connect to a host that disallows s2s
 563                                 session:close({
 564                                         condition = "policy-violation";
 565                                         text = "Server-to-server communication is not allowed to this host";
 566                                 });
 567                                 return;
 568                         end
 569                 end
 570
 571                 if session.secure and not session.cert_chain_status then check_cert_status(session); end
 572
 573                 send("<?xml version='1.0'?>");
 574                 send(stanza("stream:stream", { xmlns='jabber:server', ["xmlns:db"]='jabber:server:dialback',
 575                                 ["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());
 576                 if session.version >= 1.0 then
 577                         local features = st.stanza("stream:features");
 578
 579                         if session.to_host then
 580                                 hosts[session.to_host].events.fire_event("s2s-stream-features", { origin = session, features = features });
 581                         else
 582                                 (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");
 583                         end
 584
 585                         log("debug", "Sending stream features: %s", tostring(features));
 586                         send(features);
 587                 end
 588         elseif session.direction == "outgoing" then
 589                 -- If we are just using the connection for verifying dialback keys, we won't try and auth it
 590                 if not attr.id then error("stream response did not give us a streamid!!!"); end
 591                 session.streamid = attr.id;
 592
 593                 if session.secure and not session.cert_chain_status then check_cert_status(session); end
 594
 595                 -- Send unauthed buffer
 596                 -- (stanzas which are fine to send before dialback)
 597                 -- Note that this is *not* the stanza queue (which
 598                 -- we can only send if auth succeeds) :)
 599                 local send_buffer = session.send_buffer;
 600                 if send_buffer and #send_buffer > 0 then
 601                         log("debug", "Sending s2s send_buffer now...");
 602                         for i, data in ipairs(send_buffer) do
 603                                 session.sends2s(tostring(data));
 604                                 send_buffer[i] = nil;
 605                         end
 606                 end
 607                 session.send_buffer = nil;
 608
 609                 -- If server is pre-1.0, don't wait for features, just do dialback
 610                 if session.version < 1.0 then
 611                         if not session.dialback_verifying then
 612                                 log("debug", "Initiating dialback...");
 613                                 initiate_dialback(session);
 614                         else
 615                                 mark_connected(session);
 616                         end
 617                 end
 618         end
 619         session.notopen = nil;
 620 end
 621
 622 function streamclosed(session)
 623         (session.log or log)("debug", "Received </stream:stream>");
 624         session:close();
 625 end
 626
 627 function initiate_dialback(session)
 628         -- generate dialback key
 629         session.dialback_key = generate_dialback(session.streamid, session.to_host, session.from_host);
 630         session.sends2s(format("<db:result from='%s' to='%s'>%s</db:result>", session.from_host, session.to_host, session.dialback_key));
 631         session.log("info", "sent dialback key on outgoing s2s stream");
 632 end
 633
 634 function generate_dialback(id, to, from)
 635         return sha256_hash(id..to..from..hosts[from].dialback_secret, true);
 636 end
 637
 638 function verify_dialback(id, to, from, key)
 639         return key == generate_dialback(id, to, from);
 640 end
 641
 642 function make_authenticated(session, host)
 643         if not session.secure then
 644                 local local_host = session.direction == "incoming" and session.to_host or session.from_host;
 645                 if config.get(local_host, "core", "s2s_require_encryption") then
 646                         session:close({
 647                                 condition = "policy-violation",
 648                                 text = "Encrypted server-to-server communication is required but was not "
 649                                        ..((session.direction == "outgoing" and "offered") or "used")
 650                         });
 651                 end
 652         end
 653         if session.type == "s2sout_unauthed" then
 654                 session.type = "s2sout";
 655         elseif session.type == "s2sin_unauthed" then
 656                 session.type = "s2sin";
 657                 if host then
 658                         if not session.hosts[host] then session.hosts[host] = {}; end
 659                         session.hosts[host].authed = true;
 660                 end
 661         elseif session.type == "s2sin" and host then
 662                 if not session.hosts[host] then session.hosts[host] = {}; end
 663                 session.hosts[host].authed = true;
 664         else
 665                 return false;
 666         end
 667         session.log("debug", "connection %s->%s is now authenticated for %s", session.from_host or "(unknown)", session.to_host or "(unknown)", host);
 668
 669         mark_connected(session);
 670
 671         return true;
 672 end
 673
 674 -- Stream is authorised, and ready for normal stanzas
 675 function mark_connected(session)
 676         local sendq, send = session.sendq, session.sends2s;
 677
 678         local from, to = session.from_host, session.to_host;
 679
 680         session.log("info", session.direction.." s2s connection "..from.."->"..to.." complete");
 681
 682         local send_to_host = send_to_host;
 683         function session.send(data) return send_to_host(to, from, data); end
 684
 685         local event_data = { session = session };
 686         if session.type == "s2sout" then
 687                 prosody.events.fire_event("s2sout-established", event_data);
 688                 hosts[session.from_host].events.fire_event("s2sout-established", event_data);
 689         else
 690                 prosody.events.fire_event("s2sin-established", event_data);
 691                 hosts[session.to_host].events.fire_event("s2sin-established", event_data);
 692         end
 693
 694         if session.direction == "outgoing" then
 695                 if sendq then
 696                         session.log("debug", "sending "..#sendq.." queued stanzas across new outgoing connection to "..session.to_host);
 697                         for i, data in ipairs(sendq) do
 698                                 send(data[1]);
 699                                 sendq[i] = nil;
 700                         end
 701                         session.sendq = nil;
 702                 end
 703
 704                 session.srv_hosts = nil;
 705         end
 706 end
 707
 708 local resting_session = { -- Resting, not dead
 709                 destroyed = true;
 710                 type = "s2s_destroyed";
 711                 open_stream = function (session)
 712                         session.log("debug", "Attempt to open stream on resting session");
 713                 end;
 714                 close = function (session)
 715                         session.log("debug", "Attempt to close already-closed session");
 716                 end;
 717                 filter = function (type, data) return data; end;
 718         }; resting_session.__index = resting_session;
 719
 720 function retire_session(session, reason)
 721         local log = session.log or log;
 722         for k in pairs(session) do
 723                 if k ~= "trace" and k ~= "log" and k ~= "id" then
 724                         session[k] = nil;
 725                 end
 726         end
 727
 728         session.destruction_reason = reason;
 729
 730         function session.send(data) log("debug", "Discarding data sent to resting session: %s", tostring(data)); end
 731         function session.data(data) log("debug", "Discarding data received from resting session: %s", tostring(data)); end
 732         return setmetatable(session, resting_session);
 733 end
 734
 735 function destroy_session(session, reason)
 736         if session.destroyed then return; end
 737         (session.log or log)("debug", "Destroying "..tostring(session.direction).." session "..tostring(session.from_host).."->"..tostring(session.to_host)..(reason and (": "..reason) or ""));
 738
 739         if session.direction == "outgoing" then
 740                 hosts[session.from_host].s2sout[session.to_host] = nil;
 741                 bounce_sendq(session, reason);
 742         elseif session.direction == "incoming" then
 743                 incoming_s2s[session] = nil;
 744         end
 745
 746         local event_data = { session = session, reason = reason };
 747         if session.type == "s2sout" then
 748                 prosody.events.fire_event("s2sout-destroyed", event_data);
 749                 if hosts[session.from_host] then
 750                         hosts[session.from_host].events.fire_event("s2sout-destroyed", event_data);
 751                 end
 752         elseif session.type == "s2sin" then
 753                 prosody.events.fire_event("s2sin-destroyed", event_data);
 754                 if hosts[session.to_host] then
 755                         hosts[session.to_host].events.fire_event("s2sin-destroyed", event_data);
 756                 end
 757         end
 758
 759         retire_session(session, reason); -- Clean session until it is GC'd
 760         return true;
 761 end
 762
 763 return _M;