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 local local_addresses = require "util.net".local_addresses;
  22
  23 local s2s_destroy_session = require "core.s2smanager".destroy_session;
  24
  25 local log = module._log;
  26
  27 local sources = {};
  28 local has_ipv4, has_ipv6;
  29
  30 local dns_timeout = module:get_option_number("dns_timeout", 15);
  31 dns.settimeout(dns_timeout);
  32 local max_dns_depth = module:get_option_number("dns_max_depth", 3);
  33
  34 local s2sout = {};
  35
  36 local s2s_listener;
  37
  38
  39 function s2sout.set_listener(listener)
  40         s2s_listener = listener;
  41 end
  42
  43 local function compare_srv_priorities(a,b)
  44         return a.priority < b.priority or (a.priority == b.priority and a.weight > b.weight);
  45 end
  46
  47 function s2sout.initiate_connection(host_session)
  48         initialize_filters(host_session);
  49         host_session.version = 1;
  50
  51         -- Kick the connection attempting machine into life
  52         if not s2sout.attempt_connection(host_session) then
  53                 -- Intentionally not returning here, the
  54                 -- session is needed, connected or not
  55                 s2s_destroy_session(host_session);
  56         end
  57
  58         if not host_session.sends2s then
  59                 -- A sends2s which buffers data (until the stream is opened)
  60                 -- note that data in this buffer will be sent before the stream is authed
  61                 -- and will not be ack'd in any way, successful or otherwise
  62                 local buffer;
  63                 function host_session.sends2s(data)
  64                         if not buffer then
  65                                 buffer = {};
  66                                 host_session.send_buffer = buffer;
  67                         end
  68                         log("debug", "Buffering data on unconnected s2sout to %s", tostring(host_session.to_host));
  69                         buffer[#buffer+1] = data;
  70                         log("debug", "Buffered item %d: %s", #buffer, tostring(data));
  71                 end
  72         end
  73 end
  74
  75 function s2sout.attempt_connection(host_session, err)
  76         local to_host = host_session.to_host;
  77         local connect_host, connect_port = to_host and idna_to_ascii(to_host), 5269;
  78
  79         if not connect_host then
  80                 return false;
  81         end
  82
  83         if not err then -- This is our first attempt
  84                 log("debug", "First attempt to connect to %s, starting with SRV lookup...", to_host);
  85                 host_session.connecting = true;
  86                 local handle;
  87                 handle = adns.lookup(function (answer)
  88                         handle = nil;
  89                         host_session.connecting = nil;
  90                         if answer and #answer > 0 then
  91                                 log("debug", "%s has SRV records, handling...", to_host);
  92                                 local srv_hosts = { answer = answer };
  93                                 host_session.srv_hosts = srv_hosts;
  94                                 for _, record in ipairs(answer) do
  95                                         t_insert(srv_hosts, record.srv);
  96                                 end
  97                                 if #srv_hosts == 1 and srv_hosts[1].target == "." then
  98                                         log("debug", "%s does not provide a XMPP service", to_host);
  99                                         s2s_destroy_session(host_session, err); -- Nothing to see here
 100                                         return;
 101                                 end
 102                                 t_sort(srv_hosts, compare_srv_priorities);
 103
 104                                 local srv_choice = srv_hosts[1];
 105                                 host_session.srv_choice = 1;
 106                                 if srv_choice then
 107                                         connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
 108                                         log("debug", "Best record found, will connect to %s:%d", connect_host, connect_port);
 109                                 end
 110                         else
 111                                 log("debug", "%s has no SRV records, falling back to A/AAAA", to_host);
 112                         end
 113                         -- Try with SRV, or just the plain hostname if no SRV
 114                         local ok, err = s2sout.try_connect(host_session, connect_host, connect_port);
 115                         if not ok then
 116                                 if not s2sout.attempt_connection(host_session, err) then
 117                                         -- No more attempts will be made
 118                                         s2s_destroy_session(host_session, err);
 119                                 end
 120                         end
 121                 end, "_xmpp-server._tcp."..connect_host..".", "SRV");
 122
 123                 return true; -- Attempt in progress
 124         elseif host_session.ip_hosts then
 125                 return s2sout.try_connect(host_session, connect_host, connect_port, err);
 126         elseif host_session.srv_hosts and #host_session.srv_hosts > host_session.srv_choice then -- Not our first attempt, and we also have SRV
 127                 host_session.srv_choice = host_session.srv_choice + 1;
 128                 local srv_choice = host_session.srv_hosts[host_session.srv_choice];
 129                 connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
 130                 host_session.log("info", "Connection failed (%s). Attempt #%d: This time to %s:%d", tostring(err), host_session.srv_choice, connect_host, connect_port);
 131         else
 132                 host_session.log("info", "Failed in all attempts to connect to %s", tostring(host_session.to_host));
 133                 -- We're out of options
 134                 return false;
 135         end
 136
 137         if not (connect_host and connect_port) then
 138                 -- Likely we couldn't resolve DNS
 139                 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));
 140                 return false;
 141         end
 142
 143         return s2sout.try_connect(host_session, connect_host, connect_port);
 144 end
 145
 146 function s2sout.try_next_ip(host_session)
 147         host_session.connecting = nil;
 148         host_session.ip_choice = host_session.ip_choice + 1;
 149         local ip = host_session.ip_hosts[host_session.ip_choice];
 150         local ok, err= s2sout.make_connect(host_session, ip.ip, ip.port);
 151         if not ok then
 152                 if not s2sout.attempt_connection(host_session, err or "closed") then
 153                         err = err and (": "..err) or "";
 154                         s2s_destroy_session(host_session, "Connection failed"..err);
 155                 end
 156         end
 157 end
 158
 159 function s2sout.try_connect(host_session, connect_host, connect_port, err)
 160         host_session.connecting = true;
 161
 162         if not err then
 163                 local IPs = {};
 164                 host_session.ip_hosts = IPs;
 165                 local handle4, handle6;
 166                 local have_other_result = not(has_ipv4) or not(has_ipv6) or false;
 167
 168                 if has_ipv4 then
 169                         handle4 = adns.lookup(function (reply, err)
 170                                 handle4 = nil;
 171
 172                                 -- COMPAT: This is a compromise for all you CNAME-(ab)users :)
 173                                 if not (reply and reply[#reply] and reply[#reply].a) then
 174                                         local count = max_dns_depth;
 175                                         reply = dns.peek(connect_host, "CNAME", "IN");
 176                                         while count > 0 and reply and reply[#reply] and not reply[#reply].a and reply[#reply].cname do
 177                                                 log("debug", "Looking up %s (DNS depth is %d)", tostring(reply[#reply].cname), count);
 178                                                 reply = dns.peek(reply[#reply].cname, "A", "IN") or dns.peek(reply[#reply].cname, "CNAME", "IN");
 179                                                 count = count - 1;
 180                                         end
 181                                 end
 182                                 -- end of CNAME resolving
 183
 184                                 if reply and reply[#reply] and reply[#reply].a then
 185                                         for _, ip in ipairs(reply) do
 186                                                 log("debug", "DNS reply for %s gives us %s", connect_host, ip.a);
 187                                                 IPs[#IPs+1] = new_ip(ip.a, "IPv4");
 188                                         end
 189                                 end
 190
 191                                 if have_other_result then
 192                                         if #IPs > 0 then
 193                                                 rfc6724_dest(host_session.ip_hosts, sources);
 194                                                 for i = 1, #IPs do
 195                                                         IPs[i] = {ip = IPs[i], port = connect_port};
 196                                                 end
 197                                                 host_session.ip_choice = 0;
 198                                                 s2sout.try_next_ip(host_session);
 199                                         else
 200                                                 log("debug", "DNS lookup failed to get a response for %s", connect_host);
 201                                                 host_session.ip_hosts = nil;
 202                                                 if not s2sout.attempt_connection(host_session, "name resolution failed") then -- Retry if we can
 203                                                         log("debug", "No other records to try for %s - destroying", host_session.to_host);
 204                                                         err = err and (": "..err) or "";
 205                                                         s2s_destroy_session(host_session, "DNS resolution failed"..err); -- End of the line, we can't
 206                                                 end
 207                                         end
 208                                 else
 209                                         have_other_result = true;
 210                                 end
 211                         end, connect_host, "A", "IN");
 212                 else
 213                         have_other_result = true;
 214                 end
 215
 216                 if has_ipv6 then
 217                         handle6 = adns.lookup(function (reply, err)
 218                                 handle6 = nil;
 219
 220                                 if reply and reply[#reply] and reply[#reply].aaaa then
 221                                         for _, ip in ipairs(reply) do
 222                                                 log("debug", "DNS reply for %s gives us %s", connect_host, ip.aaaa);
 223                                                 IPs[#IPs+1] = new_ip(ip.aaaa, "IPv6");
 224                                         end
 225                                 end
 226
 227                                 if have_other_result then
 228                                         if #IPs > 0 then
 229                                                 rfc6724_dest(host_session.ip_hosts, sources);
 230                                                 for i = 1, #IPs do
 231                                                         IPs[i] = {ip = IPs[i], port = connect_port};
 232                                                 end
 233                                                 host_session.ip_choice = 0;
 234                                                 s2sout.try_next_ip(host_session);
 235                                         else
 236                                                 log("debug", "DNS lookup failed to get a response for %s", connect_host);
 237                                                 host_session.ip_hosts = nil;
 238                                                 if not s2sout.attempt_connection(host_session, "name resolution failed") then -- Retry if we can
 239                                                         log("debug", "No other records to try for %s - destroying", host_session.to_host);
 240                                                         err = err and (": "..err) or "";
 241                                                         s2s_destroy_session(host_session, "DNS resolution failed"..err); -- End of the line, we can't
 242                                                 end
 243                                         end
 244                                 else
 245                                         have_other_result = true;
 246                                 end
 247                         end, connect_host, "AAAA", "IN");
 248                 else
 249                         have_other_result = true;
 250                 end
 251                 return true;
 252         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
 253                 s2sout.try_next_ip(host_session);
 254         else
 255                 host_session.ip_hosts = nil;
 256                 if not s2sout.attempt_connection(host_session, "out of IP addresses") then -- Retry if we can
 257                         log("debug", "No other records to try for %s - destroying", host_session.to_host);
 258                         err = err and (": "..err) or "";
 259                         s2s_destroy_session(host_session, "Connecting failed"..err); -- End of the line, we can't
 260                         return false;
 261                 end
 262         end
 263
 264         return true;
 265 end
 266
 267 function s2sout.make_connect(host_session, connect_host, connect_port)
 268         (host_session.log or log)("debug", "Beginning new connection attempt to %s ([%s]:%d)", host_session.to_host, connect_host.addr, connect_port);
 269
 270         -- Reset secure flag in case this is another
 271         -- connection attempt after a failed STARTTLS
 272         host_session.secure = nil;
 273         host_session.encrypted = nil;
 274
 275         local conn, handler;
 276         local proto = connect_host.proto;
 277         if proto == "IPv4" then
 278                 conn, handler = socket.tcp();
 279         elseif proto == "IPv6" and socket.tcp6 then
 280                 conn, handler = socket.tcp6();
 281         else
 282                 handler = "Unsupported protocol: "..tostring(proto);
 283         end
 284
 285         if not conn then
 286                 log("warn", "Failed to create outgoing connection, system error: %s", handler);
 287                 return false, handler;
 288         end
 289
 290         conn:settimeout(0);
 291         local success, err = conn:connect(connect_host.addr, connect_port);
 292         if not success and err ~= "timeout" then
 293                 log("warn", "s2s connect() to %s (%s:%d) failed: %s", host_session.to_host, connect_host.addr, connect_port, err);
 294                 return false, err;
 295         end
 296
 297         conn = wrapclient(conn, connect_host.addr, connect_port, s2s_listener, "*a");
 298         host_session.conn = conn;
 299
 300         -- Register this outgoing connection so that xmppserver_listener knows about it
 301         -- otherwise it will assume it is a new incoming connection
 302         s2s_listener.register_outgoing(conn, host_session);
 303
 304         log("debug", "Connection attempt in progress...");
 305         return true;
 306 end
 307
 308 module:hook_global("service-added", function (event)
 309         if event.name ~= "s2s" then return end
 310
 311         local s2s_sources = portmanager.get_active_services():get("s2s");
 312         if not s2s_sources then
 313                 module:log("warn", "s2s not listening on any ports, outgoing connections may fail");
 314                 return;
 315         end
 316         for source, _ in pairs(s2s_sources) do
 317                 if source == "*" or source == "0.0.0.0" then
 318                         for _, addr in ipairs(local_addresses("ipv4", true)) do
 319                                 sources[#sources + 1] = new_ip(addr, "IPv4");
 320                         end
 321                 elseif source == "::" then
 322                         for _, addr in ipairs(local_addresses("ipv6", true)) do
 323                                 sources[#sources + 1] = new_ip(addr, "IPv6");
 324                         end
 325                 else
 326                         sources[#sources + 1] = new_ip(source, (source:find(":") and "IPv6") or "IPv4");
 327                 end
 328         end
 329         for i = 1,#sources do
 330                 if sources[i].proto == "IPv6" then
 331                         has_ipv6 = true;
 332                 elseif sources[i].proto == "IPv4" then
 333                         has_ipv4 = true;
 334                 end
 335         end
 336         if not (has_ipv4 or has_ipv6)  then
 337                 module:log("warn", "No local IPv4 or IPv6 addresses detected, outgoing connections may fail");
 338         end
 339 end);
 340
 341 return s2sout;