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 uuid_gen = require "util.uuid".generate;
  31
  32 local logger_init = require "util.logger".init;
  33
  34 local log = logger_init("s2smanager");
  35
  36 local sha256_hash = require "util.hashes".sha256;
  37
  38 local dialback_secret = uuid_gen();
  39
  40 local adns = require "net.adns";
  41
  42 local dns_timeout = config.get("*", "core", "dns_timeout") or 60;
  43
  44 incoming_s2s = {};
  45 local incoming_s2s = incoming_s2s;
  46
  47 module "s2smanager"
  48
  49 local function compare_srv_priorities(a,b) return a.priority < b.priority or a.weight < b.weight; end
  50
  51 local function bounce_sendq(session)
  52         local sendq = session.sendq;
  53         if sendq then
  54                 session.log("info", "sending error replies for "..#sendq.." queued stanzas because of failed outgoing connection to "..tostring(session.to_host));
  55                 local dummy = {
  56                         type = "s2sin";
  57                         send = function(s)
  58                                 (session.log or log)("error", "Replying to to an s2s error reply, please report this! Traceback: %s", get_traceback());
  59                         end;
  60                         dummy = true;
  61                 };
  62                 for i, data in ipairs(sendq) do
  63                         local reply = data[2];
  64                         local xmlns = reply.attr.xmlns;
  65                         if not xmlns or xmlns == "jabber:client" or xmlns == "jabber:server" then
  66                                 reply.attr.type = "error";
  67                                 reply:tag("error", {type = "cancel"})
  68                                         :tag("remote-server-not-found", {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"}):up();
  69                                 core_process_stanza(dummy, reply);
  70                         end
  71                         sendq[i] = nil;
  72                 end
  73                 session.sendq = nil;
  74         end
  75 end
  76
  77 function send_to_host(from_host, to_host, data)
  78         local host = hosts[from_host].s2sout[to_host];
  79         if host then
  80                 -- We have a connection to this host already
  81                 if host.type == "s2sout_unauthed" and data.name ~= "db:verify" and ((not data.xmlns) or data.xmlns == "jabber:client" or data.xmlns == "jabber:server") then
  82                         (host.log or log)("debug", "trying to send over unauthed s2sout to "..to_host);
  83                         if not host.notopen and not host.dialback_key and host.sends2s then
  84                                 host.log("debug", "dialback had not been initiated");
  85                                 initiate_dialback(host);
  86                         end
  87
  88                         -- Queue stanza until we are able to send it
  89                         if host.sendq then t_insert(host.sendq, {tostring(data), st.reply(data)});
  90                         else host.sendq = { {tostring(data), st.reply(data)} }; end
  91                         host.log("debug", "stanza [%s] queued ", data.name);
  92                 elseif host.type == "local" or host.type == "component" then
  93                         log("error", "Trying to send a stanza to ourselves??")
  94                         log("error", "Traceback: %s", get_traceback());
  95                         log("error", "Stanza: %s", tostring(data));
  96                 else
  97                         (host.log or log)("debug", "going to send stanza to "..to_host.." from "..from_host);
  98                         -- FIXME
  99                         if host.from_host ~= from_host then
 100                                 log("error", "WARNING! This might, possibly, be a bug, but it might not...");
 101                                 log("error", "We are going to send from %s instead of %s", tostring(host.from_host), tostring(from_host));
 102                         end
 103                         host.sends2s(data);
 104                         host.log("debug", "stanza sent over "..host.type);
 105                 end
 106         else
 107                 log("debug", "opening a new outgoing connection for this stanza");
 108                 local host_session = new_outgoing(from_host, to_host);
 109                 -- Store in buffer
 110                 host_session.sendq = { {tostring(data), st.reply(data)} };
 111                 log("debug", "stanza [%s] queued until connection complete", tostring(data.name));
 112                 if (not host_session.connecting) and (not host_session.conn) then
 113                         log("warn", "Connection to %s failed already, destroying session...", to_host);
 114                         destroy_session(host_session);
 115                 end
 116         end
 117 end
 118
 119 local open_sessions = 0;
 120
 121 function new_incoming(conn)
 122         local session = { conn = conn, type = "s2sin_unauthed", direction = "incoming", hosts = {} };
 123         if true then
 124                 session.trace = newproxy(true);
 125                 getmetatable(session.trace).__gc = function () open_sessions = open_sessions - 1; end;
 126         end
 127         open_sessions = open_sessions + 1;
 128         local w, log = conn.write, logger_init("s2sin"..tostring(conn):match("[a-f0-9]+$"));
 129         session.log = log;
 130         session.sends2s = function (t) log("debug", "sending: %s", tostring(t)); w(tostring(t)); end
 131         incoming_s2s[session] = true;
 132         return session;
 133 end
 134
 135 function new_outgoing(from_host, to_host)
 136                 local host_session = { to_host = to_host, from_host = from_host, notopen = true, type = "s2sout_unauthed", direction = "outgoing" };
 137                 hosts[from_host].s2sout[to_host] = host_session;
 138
 139                 local log;
 140                 do
 141                         local conn_name = "s2sout"..tostring(host_session):match("[a-f0-9]*$");
 142                         log = logger_init(conn_name);
 143                         host_session.log = log;
 144                 end
 145
 146                 -- This is the first call, can't fail (the first step is DNS lookup)
 147                 attempt_connection(host_session);
 148
 149                 if not host_session.sends2s then
 150                         -- A sends2s which buffers data (until the stream is opened)
 151                         -- note that data in this buffer will be sent before the stream is authed
 152                         -- and will not be ack'd in any way, successful or otherwise
 153                         local buffer;
 154                         function host_session.sends2s(data)
 155                                 if not buffer then
 156                                         buffer = {};
 157                                         host_session.send_buffer = buffer;
 158                                 end
 159                                 log("debug", "Buffering data on unconnected s2sout to %s", to_host);
 160                                 buffer[#buffer+1] = data;
 161                                 log("debug", "Buffered item %d: %s", #buffer, tostring(data));
 162                         end
 163
 164                 end
 165
 166                 return host_session;
 167 end
 168
 169
 170 function attempt_connection(host_session, err)
 171         local from_host, to_host = host_session.from_host, host_session.to_host;
 172         local connect_host, connect_port = idna_to_ascii(to_host), 5269;
 173
 174         if not err then -- This is our first attempt
 175                 log("debug", "First attempt to connect to %s, starting with SRV lookup...", to_host);
 176                 host_session.connecting = true;
 177                 local answer, handle;
 178                 handle = adns.lookup(function (answer)
 179                         handle = nil;
 180                         host_session.connecting = nil;
 181                         if answer then
 182                                 log("debug", to_host.." has SRV records, handling...");
 183                                 local srv_hosts = {};
 184                                 host_session.srv_hosts = srv_hosts;
 185                                 for _, record in ipairs(answer) do
 186                                         t_insert(srv_hosts, record.srv);
 187                                 end
 188                                 t_sort(srv_hosts, compare_srv_priorities);
 189
 190                                 local srv_choice = srv_hosts[1];
 191                                 host_session.srv_choice = 1;
 192                                 if srv_choice then
 193                                         connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
 194                                         log("debug", "Best record found, will connect to %s:%d", connect_host, connect_port);
 195                                 end
 196                         else
 197                                 log("debug", to_host.." has no SRV records, falling back to A");
 198                         end
 199                         -- Try with SRV, or just the plain hostname if no SRV
 200                         local ok, err = try_connect(host_session, connect_host, connect_port);
 201                         if not ok then
 202                                 if not attempt_connection(host_session, err) then
 203                                         -- No more attempts will be made
 204                                         destroy_session(host_session);
 205                                 end
 206                         end
 207                 end, "_xmpp-server._tcp."..connect_host..".", "SRV");
 208
 209                 -- Set handler for DNS timeout
 210                 add_task(dns_timeout, function ()
 211                         if handle then
 212                                 adns.cancel(handle, true);
 213                         end
 214                 end);
 215
 216                 log("debug", "DNS lookup for %s sent, waiting for response before we can connect", to_host);
 217                 return true; -- Attempt in progress
 218         elseif host_session.srv_hosts and #host_session.srv_hosts > host_session.srv_choice then -- Not our first attempt, and we also have SRV
 219                 host_session.srv_choice = host_session.srv_choice + 1;
 220                 local srv_choice = host_session.srv_hosts[host_session.srv_choice];
 221                 connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
 222                 host_session.log("info", "Connection failed (%s). Attempt #%d: This time to %s:%d", tostring(err), host_session.srv_choice, connect_host, connect_port);
 223         else
 224                 host_session.log("info", "Out of connection options, can't connect to %s", tostring(host_session.to_host));
 225                 -- We're out of options
 226                 return false;
 227         end
 228
 229         if not (connect_host and connect_port) then
 230                 -- Likely we couldn't resolve DNS
 231                 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));
 232                 return false;
 233         end
 234
 235         return try_connect(host_session, connect_host, connect_port);
 236 end
 237
 238 function try_connect(host_session, connect_host, connect_port)
 239         host_session.log("info", "Beginning new connection attempt to %s (%s:%d)", host_session.to_host, connect_host, connect_port);
 240         -- Ok, we're going to try to connect
 241
 242         local from_host, to_host = host_session.from_host, host_session.to_host;
 243
 244         local conn, handler = socket.tcp()
 245
 246         conn:settimeout(0);
 247         local success, err = conn:connect(connect_host, connect_port);
 248         if not success and err ~= "timeout" then
 249                 log("warn", "s2s connect() to %s (%s:%d) failed: %s", host_session.to_host, connect_host, connect_port, err);
 250                 return false, err;
 251         end
 252
 253         local cl = connlisteners_get("xmppserver");
 254         conn = wrapclient(conn, connect_host, connect_port, cl, cl.default_mode or 1, hosts[from_host].ssl_ctx, false );
 255         host_session.conn = conn;
 256
 257         -- Register this outgoing connection so that xmppserver_listener knows about it
 258         -- otherwise it will assume it is a new incoming connection
 259         cl.register_outgoing(conn, host_session);
 260
 261         local w = conn.write;
 262         host_session.sends2s = function (t) log("debug", "sending: %s", tostring(t)); w(tostring(t)); end
 263
 264         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));
 265         log("debug", "Connection attempt in progress...");
 266         return true;
 267 end
 268
 269 function streamopened(session, attr)
 270         local send = session.sends2s;
 271
 272         -- TODO: #29: SASL/TLS on s2s streams
 273         session.version = 0; --tonumber(attr.version) or 0;
 274
 275         if session.version >= 1.0 and not (attr.to and attr.from) then
 276                 log("warn", (session.to_host or "(unknown)").." failed to specify 'to' or 'from' hostname as per RFC");
 277         end
 278
 279         if session.direction == "incoming" then
 280                 -- Send a reply stream header
 281                 session.to_host = attr.to and nameprep(attr.to);
 282                 session.from_host = attr.from and nameprep(attr.from);
 283
 284                 session.streamid = uuid_gen();
 285                 (session.log or log)("debug", "incoming s2s received <stream:stream>");
 286                 send("<?xml version='1.0'?>");
 287                 send(stanza("stream:stream", { xmlns='jabber:server', ["xmlns:db"]='jabber:server:dialback',
 288                                 ["xmlns:stream"]='http://etherx.jabber.org/streams', id=session.streamid, from=session.to_host }):top_tag());
 289                 if session.to_host and not hosts[session.to_host] then
 290                         -- Attempting to connect to a host we don't serve
 291                         session:close({ condition = "host-unknown"; text = "This host does not serve "..session.to_host });
 292                         return;
 293                 end
 294                 if session.version >= 1.0 then
 295                         send(st.stanza("stream:features")
 296                                         :tag("dialback", { xmlns='urn:xmpp:features:dialback' }):tag("optional"):up():up());
 297                 end
 298         elseif session.direction == "outgoing" then
 299                 -- If we are just using the connection for verifying dialback keys, we won't try and auth it
 300                 if not attr.id then error("stream response did not give us a streamid!!!"); end
 301                 session.streamid = attr.id;
 302
 303                 -- Send unauthed buffer
 304                 -- (stanzas which are fine to send before dialback)
 305                 -- Note that this is *not* the stanza queue (which
 306                 -- we can only send if auth succeeds) :)
 307                 local send_buffer = session.send_buffer;
 308                 if send_buffer and #send_buffer > 0 then
 309                         log("debug", "Sending s2s send_buffer now...");
 310                         for i, data in ipairs(send_buffer) do
 311                                 session.sends2s(tostring(data));
 312                                 send_buffer[i] = nil;
 313                         end
 314                 end
 315                 session.send_buffer = nil;
 316
 317                 if not session.dialback_verifying then
 318                         initiate_dialback(session);
 319                 else
 320                         mark_connected(session);
 321                 end
 322         end
 323
 324         session.notopen = nil;
 325 end
 326
 327 function streamclosed(session)
 328         (session.log or log)("debug", "</stream:stream>");
 329         if session.sends2s then
 330                 session.sends2s("</stream:stream>");
 331         end
 332         session.notopen = true;
 333 end
 334
 335 function initiate_dialback(session)
 336         -- generate dialback key
 337         session.dialback_key = generate_dialback(session.streamid, session.to_host, session.from_host);
 338         session.sends2s(format("<db:result from='%s' to='%s'>%s</db:result>", session.from_host, session.to_host, session.dialback_key));
 339         session.log("info", "sent dialback key on outgoing s2s stream");
 340 end
 341
 342 function generate_dialback(id, to, from)
 343         return sha256_hash(id..to..from..dialback_secret, true);
 344 end
 345
 346 function verify_dialback(id, to, from, key)
 347         return key == generate_dialback(id, to, from);
 348 end
 349
 350 function make_authenticated(session, host)
 351         if session.type == "s2sout_unauthed" then
 352                 session.type = "s2sout";
 353         elseif session.type == "s2sin_unauthed" then
 354                 session.type = "s2sin";
 355                 if host then
 356                         session.hosts[host].authed = true;
 357                 end
 358         elseif session.type == "s2sin" and host then
 359                 session.hosts[host].authed = true;
 360         else
 361                 return false;
 362         end
 363         session.log("debug", "connection %s->%s is now authenticated", session.from_host or "(unknown)", session.to_host or "(unknown)");
 364
 365         mark_connected(session);
 366
 367         return true;
 368 end
 369
 370 function mark_connected(session)
 371         local sendq, send = session.sendq, session.sends2s;
 372
 373         local from, to = session.from_host, session.to_host;
 374
 375         session.log("info", session.direction.." s2s connection "..from.."->"..to.." complete");
 376
 377         local send_to_host = send_to_host;
 378         function session.send(data) send_to_host(to, from, data); end
 379
 380
 381         if session.direction == "outgoing" then
 382                 if sendq then
 383                         session.log("debug", "sending "..#sendq.." queued stanzas across new outgoing connection to "..session.to_host);
 384                         for i, data in ipairs(sendq) do
 385                                 send(data[1]);
 386                                 sendq[i] = nil;
 387                         end
 388                         session.sendq = nil;
 389                 end
 390
 391                 session.srv_hosts = nil;
 392         end
 393 end
 394
 395 function destroy_session(session)
 396         (session.log or log)("info", "Destroying "..tostring(session.direction).." session "..tostring(session.from_host).."->"..tostring(session.to_host));
 397
 398         if session.direction == "outgoing" then
 399                 hosts[session.from_host].s2sout[session.to_host] = nil;
 400                 bounce_sendq(session);
 401         elseif session.direction == "incoming" then
 402                 incoming_s2s[session] = nil;
 403         end
 404
 405         for k in pairs(session) do
 406                 if k ~= "trace" then
 407                         session[k] = nil;
 408                 end
 409         end
 410 end
 411
 412 return _M;