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 new_resolver = require "net.dns".resolver;
  11
  12 local log = require "util.logger".init("adns");
  13
  14 local coroutine, pcall = coroutine, pcall;
  15 local setmetatable = setmetatable;
  16
  17 local function dummy_send(sock, data, i, j) return (j-i)+1; end -- luacheck: ignore 212
  18
  19 local _ENV = nil;
  20 -- luacheck: std none
  21
  22 local async_resolver_methods = {};
  23 local async_resolver_mt = { __index = async_resolver_methods };
  24
  25 local query_methods = {};
  26 local query_mt = { __index = query_methods };
  27
  28 local function new_async_socket(sock, resolver)
  29         local peername = "<unknown>";
  30         local listener = {};
  31         local handler = {};
  32         function listener.onincoming(conn, data) -- luacheck: ignore 212/conn
  33                 if data then
  34                         resolver:feed(handler, data);
  35                 end
  36         end
  37         function listener.ondisconnect(conn, err)
  38                 if err then
  39                         log("warn", "DNS socket for %s disconnected: %s", peername, err);
  40                         local servers = resolver.server;
  41                         if resolver.socketset[conn] == resolver.best_server and resolver.best_server == #servers then
  42                                 log("error", "Exhausted all %d configured DNS servers, next lookup will try %s again", #servers, servers[1]);
  43                         end
  44
  45                         resolver:servfail(conn); -- Let the magic commence
  46                 end
  47         end
  48         do
  49                 local err;
  50                 handler, err = server.wrapclient(sock, "dns", 53, listener);
  51                 if not handler then
  52                         return nil, err;
  53                 end
  54         end
  55
  56         handler.settimeout = function () end
  57         handler.setsockname = function (_, ...) return sock:setsockname(...); end
  58         handler.setpeername = function (_, ...) peername = (...); local ret, err = sock:setpeername(...); _:set_send(dummy_send); return ret, err; end
  59         handler.connect = function (_, ...) return sock:connect(...) end
  60         --handler.send = function (_, data) _:write(data);  return _.sendbuffer and _.sendbuffer(); end
  61         handler.send = function (_, data)
  62                 log("debug", "Sending DNS query to %s", peername);
  63                 return sock:send(data);
  64         end
  65         return handler;
  66 end
  67
  68 function async_resolver_methods:lookup(handler, qname, qtype, qclass)
  69         local resolver = self._resolver;
  70         return coroutine.wrap(function (peek)
  71                                 if peek then
  72                                         log("debug", "Records for %s already cached, using those...", qname);
  73                                         handler(peek);
  74                                         return;
  75                                 end
  76                                 log("debug", "Records for %s not in cache, sending query (%s)...", qname, coroutine.running());
  77                                 local ok, err = resolver:query(qname, qtype, qclass);
  78                                 if ok then
  79                                         coroutine.yield(setmetatable({ resolver, qclass or "IN", qtype or "A", qname, coroutine.running()}, query_mt)); -- Wait for reply
  80                                         log("debug", "Reply for %s (%s)", qname, coroutine.running());
  81                                 end
  82                                 if ok then
  83                                         ok, err = pcall(handler, resolver:peek(qname, qtype, qclass));
  84                                 else
  85                                         log("error", "Error sending DNS query: %s", err);
  86                                         ok, err = pcall(handler, nil, err);
  87                                 end
  88                                 if not ok then
  89                                         log("error", "Error in DNS response handler: %s", err);
  90                                 end
  91                         end)(resolver:peek(qname, qtype, qclass));
  92 end
  93
  94 function query_methods:cancel(call_handler, reason) -- luacheck: ignore 212/reason
  95         log("warn", "Cancelling DNS lookup for %s", self[4]);
  96         self[1].cancel(self[2], self[3], self[4], self[5], call_handler);
  97 end
  98
  99 local function new_async_resolver()
 100         local resolver = new_resolver();
 101         resolver:socket_wrapper_set(new_async_socket);
 102         return setmetatable({ _resolver = resolver}, async_resolver_mt);
 103 end
 104
 105 return {
 106         lookup = function (...)
 107                 return new_async_resolver():lookup(...);
 108         end;
 109         resolver = new_async_resolver;
 110         new_async_socket = new_async_socket;
 111 };