net/adns.lua

   1 local server = require "net.server";
   2 local dns = require "net.dns";
   3
   4 local log = require "util.logger".init("adns");
   5
   6 local coroutine, tostring, pcall = coroutine, tostring, pcall;
   7
   8 module "adns"
   9
  10 function lookup(handler, qname, qtype, qclass)
  11         return coroutine.wrap(function (peek)
  12                                 if peek then
  13                                         log("debug", "Records for %s already cached, using those...", qname);
  14                                         handler(peek);
  15                                         return;
  16                                 end
  17                                 log("debug", "Records for %s not in cache, sending query (%s)...", qname, tostring(coroutine.running()));
  18                                 dns.query(qname, qtype, qclass);
  19                                 coroutine.yield({ qclass or "IN", qtype or "A", qname, coroutine.running()}); -- Wait for reply
  20                                 log("debug", "Reply for %s (%s)", qname, tostring(coroutine.running()));
  21                                 local ok, err = pcall(handler, dns.peek(qname, qtype, qclass));
  22                                 if not ok then
  23                                         log("debug", "Error in DNS response handler: %s", tostring(err));
  24                                 end
  25                         end)(dns.peek(qname, qtype, qclass));
  26 end
  27
  28 function cancel(handle, call_handler)
  29         dns.cancel(handle);
  30         if call_handler then
  31                 handle[4]()
  32         end
  33 end
  34
  35 function new_async_socket(sock)
  36         local newconn = {};
  37         local listener = {};
  38         function listener.incoming(conn, data)
  39                 dns.feed(sock, data);
  40         end
  41         function listener.disconnect()
  42         end
  43         newconn.handler, newconn._socket = server.wrapclient(sock, "dns", 53, listener);
  44         newconn.handler.settimeout = function () end
  45         newconn.handler.setsockname = function (_, ...) return sock:setsockname(...); end
  46         newconn.handler.setpeername = function (_, ...) local ret = sock:setpeername(...); _.setsend(sock.send); return ret; end
  47         newconn.handler.connect = function (_, ...) return sock:connect(...) end
  48         newconn.handler.send = function (_, data) _.write(data); return _.sendbuffer(); end
  49         return newconn.handler;
  50 end
  51
  52 dns:socket_wrapper_set(new_async_socket);
  53
  54 return _M;