plugins/mod_s2s/s2sout.lib.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 --- Module containing all the logic for connecting to a remote server
  10
  11 local portmanager = require "core.portmanager";
  12 local wrapclient = require "net.server".wrapclient;
  13 local initialize_filters = require "util.filters".initialize;
  14 local idna_to_ascii = require "util.encodings".idna.to_ascii;
  15 local new_ip = require "util.ip".new_ip;
  16 local rfc6724_dest = require "util.rfc6724".destination;
  17 local socket = require "socket";
  18 local adns = require "net.adns";
  19 local dns = require "net.dns";
  20 local t_insert, t_sort, ipairs = table.insert, table.sort, ipairs;
  21
  22 local s2s_destroy_session = require "core.s2smanager".destroy_session;
  23
  24 local log = module._log;
  25
  26 local anysource = { IPv4 = "0.0.0.0", IPv6 = "::" };
  27 local function get_sources(addrs)
  28         local sources = {};
  29         for _, IP in ipairs(addrs) do
  30                 local sock;
  31                 if IP.proto == "IPv4" then
  32                         sock = socket.udp();
  33                 elseif IP.proto == "IPv6" then
  34                         sock = socket.udp6();
  35                 end
  36                 sock:setpeername(IP.addr, 9);
  37                 local localaddr = sock:getsockname() or anysource[IP.proto];
  38                 sock:close();
  39                 if not sources[localaddr] then
  40                         sources[localaddr] = true;
  41                         t_insert(sources, new_ip(localaddr, IP.proto));
  42                 end
  43         end
  44         return sources;
  45 end
  46 local has_ipv4, has_ipv6;
  47
  48 local dns_timeout = module:get_option_number("dns_timeout", 15);
  49 dns.settimeout(dns_timeout);
  50
  51 local s2sout = {};
  52
  53 local s2s_listener;
  54
  55
  56 function s2sout.set_listener(listener)
  57         s2s_listener = listener;
  58 end
  59
  60 local function compare_srv_priorities(a,b)
  61         return a.priority < b.priority or (a.priority == b.priority and a.weight > b.weight);
  62 end
  63
  64 function s2sout.initiate_connection(host_session)
  65         initialize_filters(host_session);
  66         host_session.version = 1;
  67
  68         -- Kick the connection attempting machine into life
  69         if not s2sout.attempt_connection(host_session) then
  70                 -- Intentionally not returning here, the
  71                 -- session is needed, connected or not
  72                 s2s_destroy_session(host_session);
  73         end
  74
  75         if not host_session.sends2s then
  76                 -- A sends2s which buffers data (until the stream is opened)
  77                 -- note that data in this buffer will be sent before the stream is authed
  78                 -- and will not be ack'd in any way, successful or otherwise
  79                 local buffer;
  80                 function host_session.sends2s(data)
  81                         if not buffer then
  82                                 buffer = {};
  83                                 host_session.send_buffer = buffer;
  84                         end
  85                         log("debug", "Buffering data on unconnected s2sout to %s", tostring(host_session.to_host));
  86                         buffer[#buffer+1] = data;
  87                         log("debug", "Buffered item %d: %s", #buffer, tostring(data));
  88                 end
  89         end
  90 end
  91
  92 function s2sout.attempt_connection(host_session, err)
  93         local to_host = host_session.to_host;
  94         local connect_host, connect_port = to_host and idna_to_ascii(to_host), 5269;
  95
  96         if not connect_host then
  97                 return false;
  98         end
  99
 100         if not err then -- This is our first attempt
 101                 log("debug", "First attempt to connect to %s, starting with SRV lookup...", to_host);
 102                 host_session.connecting = true;
 103                 local handle;
 104                 handle = adns.lookup(function (answer)
 105                         handle = nil;
 106                         local srv_hosts = { answer = answer };
 107                         host_session.srv_hosts = srv_hosts;
 108                         host_session.srv_choice = 0;
 109                         host_session.connecting = nil;
 110                         if answer and #answer > 0 then
 111                                 log("debug", "%s has SRV records, handling...", to_host);
 112                                 for _, record in ipairs(answer) do
 113                                         t_insert(srv_hosts, record.srv);
 114                                 end
 115                                 if #srv_hosts == 1 and srv_hosts[1].target == "." then
 116                                         log("debug", "%s does not provide a XMPP service", to_host);
 117                                         s2s_destroy_session(host_session, err); -- Nothing to see here
 118                                         return;
 119                                 end
 120                                 t_sort(srv_hosts, compare_srv_priorities);
 121
 122                                 local srv_choice = srv_hosts[1];
 123                                 host_session.srv_choice = 1;
 124                                 if srv_choice then
 125                                         connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
 126                                         log("debug", "Best record found, will connect to %s:%d", connect_host, connect_port);
 127                                 end
 128                         else
 129                                 log("debug", "%s has no SRV records, falling back to A/AAAA", to_host);
 130                         end
 131                         -- Try with SRV, or just the plain hostname if no SRV
 132                         local ok, err = s2sout.try_connect(host_session, connect_host, connect_port);
 133                         if not ok then
 134                                 if not s2sout.attempt_connection(host_session, err) then
 135                                         -- No more attempts will be made
 136                                         s2s_destroy_session(host_session, err);
 137                                 end
 138                         end
 139                 end, "_xmpp-server._tcp."..connect_host..".", "SRV");
 140
 141                 return true; -- Attempt in progress
 142         elseif host_session.ip_hosts then
 143                 return s2sout.try_connect(host_session, connect_host, connect_port, err);
 144         elseif host_session.srv_hosts and #host_session.srv_hosts > host_session.srv_choice then -- Not our first attempt, and we also have SRV
 145                 host_session.srv_choice = host_session.srv_choice + 1;
 146                 local srv_choice = host_session.srv_hosts[host_session.srv_choice];
 147                 connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
 148                 host_session.log("info", "Connection failed (%s). Attempt #%d: This time to %s:%d", tostring(err), host_session.srv_choice, connect_host, connect_port);
 149         else
 150                 host_session.log("info", "Failed in all attempts to connect to %s", tostring(host_session.to_host));
 151                 -- We're out of options
 152                 return false;
 153         end
 154
 155         if not (connect_host and connect_port) then
 156                 -- Likely we couldn't resolve DNS
 157                 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));
 158                 return false;
 159         end
 160
 161         return s2sout.try_connect(host_session, connect_host, connect_port);
 162 end
 163
 164 function s2sout.try_next_ip(host_session)
 165         host_session.connecting = nil;
 166         host_session.ip_choice = host_session.ip_choice + 1;
 167         local ip = host_session.ip_hosts[host_session.ip_choice];
 168         local ok, err= s2sout.make_connect(host_session, ip.ip, ip.port);
 169         if not ok then
 170                 if not s2sout.attempt_connection(host_session, err or "closed") then
 171                         err = err and (": "..err) or "";
 172                         s2s_destroy_session(host_session, "Connection failed"..err);
 173                 end
 174         end
 175 end
 176
 177 function s2sout.try_connect(host_session, connect_host, connect_port, err)
 178         host_session.connecting = true;
 179
 180         if not err then
 181                 local IPs = {};
 182                 host_session.ip_hosts = IPs;
 183                 local handle4, handle6;
 184                 local have_other_result = not(has_ipv4) or not(has_ipv6) or false;
 185
 186                 if has_ipv4 then
 187                         handle4 = adns.lookup(function (reply, err)
 188                                 handle4 = nil;
 189
 190                                 if reply and reply[#reply] and reply[#reply].a then
 191                                         for _, ip in ipairs(reply) do
 192                                                 log("debug", "DNS reply for %s gives us %s", connect_host, ip.a);
 193                                                 IPs[#IPs+1] = new_ip(ip.a, "IPv4");
 194                                         end
 195                                 end
 196
 197                                 if have_other_result then
 198                                         if #IPs > 0 then
 199                                                 rfc6724_dest(host_session.ip_hosts, get_sources(host_session.ip_hosts));
 200                                                 for i = 1, #IPs do
 201                                                         IPs[i] = {ip = IPs[i], port = connect_port};
 202                                                 end
 203                                                 host_session.ip_choice = 0;
 204                                                 s2sout.try_next_ip(host_session);
 205                                         else
 206                                                 log("debug", "DNS lookup failed to get a response for %s", connect_host);
 207                                                 host_session.ip_hosts = nil;
 208                                                 if not s2sout.attempt_connection(host_session, "name resolution failed") then -- Retry if we can
 209                                                         log("debug", "No other records to try for %s - destroying", host_session.to_host);
 210                                                         err = err and (": "..err) or "";
 211                                                         s2s_destroy_session(host_session, "DNS resolution failed"..err); -- End of the line, we can't
 212                                                 end
 213                                         end
 214                                 else
 215                                         have_other_result = true;
 216                                 end
 217                         end, connect_host, "A", "IN");
 218                 else
 219                         have_other_result = true;
 220                 end
 221
 222                 if has_ipv6 then
 223                         handle6 = adns.lookup(function (reply, err)
 224                                 handle6 = nil;
 225
 226                                 if reply and reply[#reply] and reply[#reply].aaaa then
 227                                         for _, ip in ipairs(reply) do
 228                                                 log("debug", "DNS reply for %s gives us %s", connect_host, ip.aaaa);
 229                                                 IPs[#IPs+1] = new_ip(ip.aaaa, "IPv6");
 230                                         end
 231                                 end
 232
 233                                 if have_other_result then
 234                                         if #IPs > 0 then
 235                                                 rfc6724_dest(host_session.ip_hosts, get_sources(host_session.ip_hosts));
 236                                                 for i = 1, #IPs do
 237                                                         IPs[i] = {ip = IPs[i], port = connect_port};
 238                                                 end
 239                                                 host_session.ip_choice = 0;
 240                                                 s2sout.try_next_ip(host_session);
 241                                         else
 242                                                 log("debug", "DNS lookup failed to get a response for %s", connect_host);
 243                                                 host_session.ip_hosts = nil;
 244                                                 if not s2sout.attempt_connection(host_session, "name resolution failed") then -- Retry if we can
 245                                                         log("debug", "No other records to try for %s - destroying", host_session.to_host);
 246                                                         err = err and (": "..err) or "";
 247                                                         s2s_destroy_session(host_session, "DNS resolution failed"..err); -- End of the line, we can't
 248                                                 end
 249                                         end
 250                                 else
 251                                         have_other_result = true;
 252                                 end
 253                         end, connect_host, "AAAA", "IN");
 254                 else
 255                         have_other_result = true;
 256                 end
 257                 return true;
 258         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
 259                 s2sout.try_next_ip(host_session);
 260         else
 261                 host_session.ip_hosts = nil;
 262                 if not s2sout.attempt_connection(host_session, "out of IP addresses") then -- Retry if we can
 263                         log("debug", "No other records to try for %s - destroying", host_session.to_host);
 264                         err = err and (": "..err) or "";
 265                         s2s_destroy_session(host_session, "Connecting failed"..err); -- End of the line, we can't
 266                         return false;
 267                 end
 268         end
 269
 270         return true;
 271 end
 272
 273 function s2sout.make_connect(host_session, connect_host, connect_port)
 274         (host_session.log or log)("debug", "Beginning new connection attempt to %s ([%s]:%d)", host_session.to_host, connect_host.addr, connect_port);
 275
 276         -- Reset secure flag in case this is another
 277         -- connection attempt after a failed STARTTLS
 278         host_session.secure = nil;
 279         host_session.encrypted = nil;
 280
 281         local conn, handler;
 282         local proto = connect_host.proto;
 283         if proto == "IPv4" then
 284                 conn, handler = socket.tcp();
 285         elseif proto == "IPv6" and socket.tcp6 then
 286                 conn, handler = socket.tcp6();
 287         else
 288                 handler = "Unsupported protocol: "..tostring(proto);
 289         end
 290
 291         if not conn then
 292                 log("warn", "Failed to create outgoing connection, system error: %s", handler);
 293                 return false, handler;
 294         end
 295
 296         conn:settimeout(0);
 297         local success, err = conn:connect(connect_host.addr, connect_port);
 298         if not success and err ~= "timeout" then
 299                 log("warn", "s2s connect() to %s (%s:%d) failed: %s", host_session.to_host, connect_host.addr, connect_port, err);
 300                 return false, err;
 301         end
 302
 303         conn = wrapclient(conn, connect_host.addr, connect_port, s2s_listener, "*a");
 304         host_session.conn = conn;
 305
 306         -- Register this outgoing connection so that xmppserver_listener knows about it
 307         -- otherwise it will assume it is a new incoming connection
 308         s2s_listener.register_outgoing(conn, host_session);
 309
 310         log("debug", "Connection attempt in progress...");
 311         return true;
 312 end
 313
 314 module:hook_global("service-added", function (event)
 315         if event.name ~= "s2s" then return end
 316
 317         local s2s_sources = portmanager.get_active_services():get("s2s");
 318         if not s2s_sources then
 319                 module:log("warn", "s2s not listening on any ports, outgoing connections may fail");
 320                 return;
 321         end
 322         for source, _ in pairs(s2s_sources) do
 323                 if source:find(":") then
 324                         has_ipv6 = true;
 325                 else
 326                         has_ipv4 = true;
 327                 end
 328         end
 329 end);
 330
 331 return s2sout;