net/adns.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 local server = require "net.server";
  10 local dns = require "net.dns";
  11
  12 local log = require "util.logger".init("adns");
  13
  14 local coroutine, tostring, pcall = coroutine, tostring, pcall;
  15
  16 local function dummy_send(sock, data, i, j) return (j-i)+1; end
  17
  18 local _ENV = nil;
  19
  20 local function lookup(handler, qname, qtype, qclass)
  21         return coroutine.wrap(function (peek)
  22                                 if peek then
  23                                         log("debug", "Records for %s already cached, using those...", qname);
  24                                         handler(peek);
  25                                         return;
  26                                 end
  27                                 log("debug", "Records for %s not in cache, sending query (%s)...", qname, tostring(coroutine.running()));
  28                                 local ok, err = dns.query(qname, qtype, qclass);
  29                                 if ok then
  30                                         coroutine.yield({ qclass or "IN", qtype or "A", qname, coroutine.running()}); -- Wait for reply
  31                                         log("debug", "Reply for %s (%s)", qname, tostring(coroutine.running()));
  32                                 end
  33                                 if ok then
  34                                         ok, err = pcall(handler, dns.peek(qname, qtype, qclass));
  35                                 else
  36                                         log("error", "Error sending DNS query: %s", err);
  37                                         ok, err = pcall(handler, nil, err);
  38                                 end
  39                                 if not ok then
  40                                         log("error", "Error in DNS response handler: %s", tostring(err));
  41                                 end
  42                         end)(dns.peek(qname, qtype, qclass));
  43 end
  44
  45 local function cancel(handle, call_handler, reason)
  46         log("warn", "Cancelling DNS lookup for %s", tostring(handle[3]));
  47         dns.cancel(handle[1], handle[2], handle[3], handle[4], call_handler);
  48 end
  49
  50 local function new_async_socket(sock, resolver)
  51         local peername = "<unknown>";
  52         local listener = {};
  53         local handler = {};
  54         local err;
  55         function listener.onincoming(conn, data)
  56                 if data then
  57                         dns.feed(handler, data);
  58                 end
  59         end
  60         function listener.ondisconnect(conn, err)
  61                 if err then
  62                         log("warn", "DNS socket for %s disconnected: %s", peername, err);
  63                         local servers = resolver.server;
  64                         if resolver.socketset[conn] == resolver.best_server and resolver.best_server == #servers then
  65                                 log("error", "Exhausted all %d configured DNS servers, next lookup will try %s again", #servers, servers[1]);
  66                         end
  67
  68                         resolver:servfail(conn); -- Let the magic commence
  69                 end
  70         end
  71         handler, err = server.wrapclient(sock, "dns", 53, listener);
  72         if not handler then
  73                 return nil, err;
  74         end
  75
  76         handler.settimeout = function () end
  77         handler.setsockname = function (_, ...) return sock:setsockname(...); end
  78         handler.setpeername = function (_, ...) peername = (...); local ret, err = sock:setpeername(...); _:set_send(dummy_send); return ret, err; end
  79         handler.connect = function (_, ...) return sock:connect(...) end
  80         --handler.send = function (_, data) _:write(data);  return _.sendbuffer and _.sendbuffer(); end
  81         handler.send = function (_, data)
  82                 log("debug", "Sending DNS query to %s", peername);
  83                 return sock:send(data);
  84         end
  85         return handler;
  86 end
  87
  88 dns.socket_wrapper_set(new_async_socket);
  89
  90 return {
  91         lookup = lookup;
  92         cancel = cancel;
  93         new_async_socket = new_async_socket;
  94 };